A Learning Experience

Mari was sitting with Hero on her bed. Today was...going to be a bit difficult.
Sunny had caught them...doing it. Poor boy heard Mari letting out strange sounds and ran into the room thinking Hero was hurting her or something. That wasn't a very fun discussion. And Mari made the mistake of telling him how good it felt, and she was doing it because she loved Hero, and he loved her. And than Sunny asked if they loved him. Mari patted his head and told him of course, but this was a very different kind of love. Sunny was insistent. "Please? I love you two, too..." Mari was hesitant, and Hero seemed uncomfortable with the idea. "We'll think about it."
Sunny was her little brother, and that would be weird for her to be doing things with him. And yet...the idea excited her. A part of her actually wanted to rush into this, and try all sorts of things with her cute little brother. But before she could, she wanted to know how Hero felt about it.
Hero was obviously concerned about it, for reasons beyond incest. But if Mari really wanted to do this, than he'd join in to be a neutral party in this.
They spent a solid week of discussing and if they were actually going to do it, and found that Sunny and Mari's parents would be gone for the weekend. Considering where they were sitting right now, they agreed. Mari's nerves were beyond frayed, but she did her best to stay concentrated.
...
At last, the door opened and Sunny came in. Cliff-faced as usual...but he seemed a bit shaky as he closed the door. "Be sure to lock it." She called over to him. Sunny locked the door, and walked over, climbing onto the foot of the bed. The tension was so thick Mari felt like she was choking on it.
"So, Sunny." Hero decided to speak first. "Are you absolutely sure you want to do this?" Sunny nodded, but couldn't look up at them. "Sunny." Hero reached over and put a hand on his shoulder. Sunny flinched, but raised his head. Hero spoke in a stern voice. "This is going to be uncomfortable at first, and you might not like it. Be sure to tell us if we're doing something that makes you feel bad. Promise?" Sunny nodded with more conviction.
"Okay..." Hero still seemed uneasy.
Mari decided this was her turn. "So...I guess I'll take my clothes off?" Mari started to undress. She had done so in front of Sunny before, but now it suddenly felt very wrong to do. And she was taking off her panties and bra. Sunny seemed so composed up to that point, now staring away from her with an embarrassed look. "Sunny, you're going to be seeing a lot more of me like this. If you can't get used to it, we'll have to stop here." Sunny lifted his eyes up to meet her bits before moving to her face. He was blushing. Mari gave him a warm smile to try and help calm him down.

"Mari, how are we going to do this?" Mari's smile twitched into something not warm as she turned. "Hero, we're going to do this the way we discussed, obviously." Hero raised an eyebrow. They didn't discuss this, was she trying to make Sunny think they had this all figured out or something? He called her bluff. "Okay, go right ahead with step one." Mari paused for a moment, before deciding what to do next. She climbed onto the bed next to Hero, with Sunny in front of her. Mari took a deep breath and tried to psych herself up. "Okay...Sunny, look over here." Mari spread her legs, revealing her whole body to Sunny. He looked at her, curiosity overtaking shame. "C-closer." She said, embarrassed. Her composure was not helped by the snickering coming from her left. Sunny inched closer on all fours, his head now between her knees. The thought of trapping his head with them popped into mind, but not now. "Sunny...look here." She moved one of her hands over...and after a moment of working through the incredible embarrassment and shame of showing this to her little brother, she spread her folds open with her fingers so he could see inside her. Sunny's eyes went wide, and somehow the "Woah, Mari." she heard from Hero was worse than presenting herself in full view of Sunny.
"S-so!" Mari yelped, before stopping to take deep breaths. Sunny continued to stare at the pinkish fold in front of him. It looked weird...he wanted to touch it, but he should probably wait for Mari's instructions. Hero looked like he was both embarrassed, ashamed, and having a whale of a time.

"Okay...so, Sunny. This is...a vagina. You're supposed to...er, Hero is going to, but his...yeah..." Mari was mumbling. She hadn't realized how embarrassing this was actually going to be. She felt like a kid again, laughing at the funny words in school. Sunny had more composure than she did, seeing as how he hasn't looked away yet. "So, Mari. How about throwing in the towel?" Hero threw her a lifeline.
Yes, a hundred times yes, get her out of this! "N-no...It's fine..." She murmured instead. "Alright...let me know if I can help." Hero almost bit his tongue when he realized what he just opened himself up to.
"Actually...maybe you could help him with what you guys have?" She giggled as she finished that. Anything to get the spotlight off her. Sunny had been inching closer to between her legs, but pulled himself up to look at Hero.
"Ack, kind of did that to myself." Hero silently berated himself as he closed his eyes. Professional. Mari was doing it like this, he could too.
But first. "Sunny, I'd like to say this again. If we do anything you don't like, tell us and we'll stop, no matter when you tell us too." He looked Sunny in the eye as he said this. Sunny's usual blank face gave way to what looked like determination. He nodded.
"Alright, I'll take off my pants and underwear then." Hero did as he said, revealing his flaccid dick. Sunny looked at it, confused but also awed. Hero couldn't help but nervously smile. "Sunny, you seem really excited to learn about all this. Can you tell us why?"

Sunny paused for a moment. "Well...Mari talked about how...good it felt, and...I want to help her feel good too...to be...helpful..." Hero and Mari listened to that. Hero was stuck between "aww" and laughing hysterically. Mari only felt even more ashamed, why did she have to tell him how good it felt? She only did it to convince him Hero wasn't hurting her, but he had to-
"I'd say that's a very admirable goal." Hero said in the cheekiest voice Mari had ever heard from him. "Mari, do you think he could?" Mari's face lit up like a lighthouse. "He's my brother!" She whisper yelled, which certainly wiped the grin off Hero's face. "O-oh, right, sorry." Hero mumbled.
"Ahem, so! You see how it's soft like this, and looks easy to move?" Sunny nodded. "Well, this is where Mari comes in, if she wants to that is." Mari stumbled. "O-oh, we're going to show him that?" Mari knew they were going to teach him some things, but to demonstrate it was... "We don't have to." If Hero was as uneasy about this as she was, he was better at hiding it. Until they heard Sunny's voice say "P-please? I-I want to know. They turned to see him looking at them pleadingly. They looked back at each other. "Alright..." Mari spoke. So she'd have to...yeah...

Mari put her hand on Hero's dick. She also moved her head up and he turned his to meet. Mari pressed her mouth against his and they started to kiss. Sunny's face lit up. They were kissing...Kel said stuff like that's gross, but Hero and Mari are doing it...wouldn't be the first time Kel was wrong.
Eventually Mari's hand started feeling something more solid, Hero's erection at full size. She kept kissing him, though. Oh, Hero...~
Mari only pulled back when she saw Sunny staring at them, his breathing seemed uneven.
Hero was a bit sad she stopped, but snapped himself back into professional mode. "Alright, notice how it got bigger?" Sunny nodded, looing at it with an odd expression. "Once it's like this," Hero paused to take a condom from the desk. "You put on one of these." Sunny followed Hero's movements. "And then...well...yeah..." It suddenly hit Hero that he was taking Sunny step by step on how he has sex with his big sister.
He couldn't keep his professionalism up after that hit him. "Y-yeah..." Mari stepped in, or rather climbed on him, pushing her back against his chest. "W-woah!" Hero wasn't expecting that, let alone seeing Mari wet enough to be dripping on him. Mari held herself over his penis, right up to her vagina. "And then...this goes in here." She emphasized this by lowering herself onto it, feeling it slide in easily. "Oh..." She moaned.

Sunny's eyes felt like saucers. It actually went in! He could see an outline where Hero's penis was, almost like it was too big. Was that why she made that sound? Sunny felt worried. "D-does it hurt?" He asked with an edge of worry in his voice. "O-oh, of course it doesn't, not if we do it carefully.".
Mari shivered. She wanted Hero to move so badly. "H-Hero, we should start moving." Hero seemed a bit surprised and whispered in her ear "We've never done it in a position like this." Mari answered "Try holding me under my arms and lift me up and down. I'll help."
Sunny watched as Hero slowly lifted her up and down, and Mari bounced like it was a seesaw. "A-alright..." Mari spoke in an odd tone. "S-see how, it goes in and out? This is-oh-how you d-do it...ah..." Mari tried to continue instructing, but was interrupted by Hero's motions. She looked to see Sunny following her movements with his eyes. Up, and down. In, and out. Sometimes gazing at her face, other times where her and Hero were linked, wonder written in his eyes. Mari felt something weird. Sunny was...so cute...and Hero was so good, it felt so...
"Ah-ohh..." Mari felt herself climax way sooner than she should have, shame flooding her, and out of her. Hero picked up on that. "My, Mari. Is something the matter?" Mari could only mutter a "F-fine.." as she continued letting out soft sounds. "A-are you okay, Mari?" Sunny asked. "Don't worry..." Hero said in a strained voice, feeling really good himself. Hero had an idea, and moved one of his arms under hers, and put a hand on her chin. He lifted it up to his face, and gave her a deep kiss. Mari melted in his mouth. "Oh...mmm...mmhmm...mmero...ahh..."

Sunny felt so strange. He felt weird this whole time, but now he felt something...in his shorts... Mari was so pretty, Hero was so...wow...and they looked so... Both of them were letting out strange noises now, probably not focusing on him. Sunny reached his hand down to his shorts. He felt something hard. Oh...was he also...?
His train of thought was interrupted by Mari letting out louder sounds, followed shortly by a harsh gasp from Hero. Did something happen?
Hero lifted Mari up, letting Sunny see the thing Hero put on filled with a weird...liquid? Slime? It looked murky...
"M-Mari? Hero?" Sunny tried calling out. They were still breathing heavily, probably not having heard him.
Mari slowly moved herself on her knees and moved her head over Hero's dick. His eyes widened as she started licking it, and...oh-oh...
Sunny crossed his legs with his hands on his lap, feeling something hard under his palm.
...
After a minute or so, Hero and Mari seemed to realize Sunny was still there. "O-oh!" Mari exclaimed. She didn't know how to end this, and looked to Hero for help "S-so...a-any questions?" Hero suggested.
Sunny paused, hands still on his lap. He had two questions that were burning in his head. Sadly, he thinks they'll say no to the first one. Mari didn't seem to want him doing that with her...
So he asked the second one. "Could I...try that with...Her...o...?" He got quieter as he spoke.
...
"What?" Mari bluntly asked. Sunny's posture shriveled up in front of them. "I-I'm sorry, I shouldn't have asked, I'm sorry, I'm-" Mari quickly put a hand on his shoulder, causing him to freeze up. "Sorry, I just got surprised!" She quickly tried to calm him. "But...hehe, I thought for sure you'd ask to do that with..." Mari trialed off as she realized he probably knew she'd say no.
...Could he?
Mari turned to Hero. Hero's eyes widened when he realized what she was about to say. "Mari, he's still-" Mari moved back and put a finger on his lip to shush him. "Sunny's probably feeling really pent up after all that...we can't just leave him like that." Hero did not like the look on her face. "Mari, I'm sorry...but I'll have to stop you here. He's-"
Whatever Hero was about to say was stopped by a loud sniffle. They turned to see Sunny with a sad look on his face...and a very noticeable tent in his shorts. He looked at them and asked "Ple-please?"
...One of these days, Hero really needed to learn how to say no, even if it hurts people.
"Sunny, are you sure?" Sunny gently nodded. "Are you absolutely sure?" Sunny nodded again. "Sunny, look at me." Sunny looked up into Hero's eyes. "Are you 100%, absolutely, completely sure you want to do this?" Sunny faltered for a moment...but nodded.
"Yes...I do."
...
Hero had put on a different condom as Mari got to work. Seems she had bought a special lube for if they had ever wanted to try something like this together. She never thought she'd be putting it on and in her li-S-Sunny. Don't call him that, it's more embarrassing.
"Sunny, I once again would like to remind you." Hero felt like a broken record, having said this 5 more times already. "This probably won't feel good, and you'll probably hate it. Are you sure you want to do this?" Sunny nodded, for the 6th time with a slightly annoyed look.
"If you don't want me to, you could tell me." He said in the closest Sunny could get to a biting tone.
Sigh...this is going to be interesting. "Sunny...I'm going to stick my fingers up your butt. Are you really, really okay with this?"
"Yes."
"Then in they go." Coated in a special liquid, Mari pushed her fingers in. Sunny let out an "A-ah-" It felt weird...
Mari kept moving her fingers around, almost caressing his insides with it. After a minute, she pulled out, cleaned her fingers in a nearby water dish, used a paper towel, dipped them in more lube, and stuck them back in. "Ah..." Sunny moaned again. Mari hoped she was doing this right. Even if she could work up the courage, she had no idea who to ask about this kind of thing, so she was just doing what sounded right. Mari tried to focus on coating as much of it in him and as deeply in him as possible, and not on the super adorable noises he was making and desire to see his no doubt cute face. Mari kept adding more and more inside him, and she heard him make even cuter squeaks and sounds. "Ah-eh...Mari, that's...ah-oh..."
Mari...felt like a switch flipped in her head. She almost felt like dragging this out to coax more sounds out of him...or something else.
She couldn't help but notice his painful erection, looking like it was about to burst.
Hero looked at her with an odd expression, eyebrow raised. O-oh, guess that means she's gone on long enough, hehe...
After coating what might have been 3 or more layers as deeply as her index and middle finger could reach, she pulled out for the last time.
"Okay, Hero. He's ready." Mari said, nervousness bleeding into her voice. "S-Sunny...are you sure-" Sunny for once interrupted her. "Yes." Mari stopped herself, and helped lift him over Hero.

"Mari, are you sure you're okay with me doing this? He IS your little brother." Hero felt uneasy, worried about hurting Sunny. Mari, through her nervousness, gave a gentle smile. "Hero, I trust you. I know how gentle you can be, you aren't going to hurt him."
"Okay..." Hero replied, as he slowly lowered Sunny. He felt an entrance, and spread it open as he pushed in, as slowly and gently as possible.
"Nghh..." Sunny groaned, an odd look twisted his face. Sunny's hole was incredibly tight, but all the lube caused surprisingly little friction. Mari started to hold Sunny's hand. "There, there. You're doing great." Part of her felt like what she was saying was bad, but wanted to encourage Sunny.
Sunny rested on Hero's lap, having taken him in completely. "Does this feel okay?" Hero petted Sunny's head. After a moment Sunny nodded. Mari squeezed his hand. "Good boy, Sunny." Mari decided to sit as close to Sunny and Hero as possible, squeezing Sunny against Hero and wrapping her legs around both of them in some kind of grip. This position had Sunny sandwiched between Hero and Mari, his penis being pushed against her belly.
"Sunny, I'm going to move again."
Sunny felt his insides close up, before being spread open. It felt so weird, but good...the feeling of his insides being filled, his penis rubbing against Mari's belly, and how warm he felt being squished between them. Sunny's voice started leaking, letting out "ah-oh-mmm, nghh" noises, both pleasure and strain. He tried to look at Hero occasionally, but found his attention mostly on Mari's adoring face.
She looked...so happy, proud of him...? He...he liked this...
"Hero, do you mind if I try something with him?"
"Sure, he's your brother."
"Thank you."
Mari's face got closer to Sunny's. She pressed her lips against his mouth and opened them, before her tongue entered his mouth. Sunny surrendered himself to them. Sunny felt Mari play with his tongue, contorting inside his mouth and touching every last part. Whenever he could open his eyes, she was always staring right at him. But he'd quickly close them. Everything was so overwhelming right now, his penis rubbing against Mari, her tongue invading his mouth, Hero spreading his insides wide and filling him, how warm his penis felt, Sunny just wanted to get lost in this feeling forever.

Hero was mostly focusing on making sure this was as easy for Sunny as possible, and not to hurt him. But he couldn't deny that he was enjoying this a bit more than he should. As gross as it felt to think, Sunny's insides felt good. "Sunny, I'm going to start speeding up a little." Not by too much. Up and down in a rhythmic motion, making sure to not go too fast and cause pain.
Mari felt so overjoyed right now. Sunny was making the cutest expressions under her. She was enjoying this way more than she should. But seeing Sunny so overstimulated, seeing his cute faces as he made even more adorable sounds, feeling his hardness rub against her and occasionally spurting small bits of semen, seeing him open his teary eyes and look at her with so much pleasure in them, all for her. Mari decided to pull away, and unplugged Sunny's moans. "Ahh-ahh-hhghh-I-ah-" Mari giggled. "Does it feel that good?" Mari couldn't tell if he was responding or not. "Hehe, poor Sunny's mind is going blank. Hero, when did you get so good at this?" Before Hero could respond, she quickly gave him a kiss herself. Even though she had surprised him, Hero quickly gained control of the kiss and started overwhelming Mari. Jeez, she could never win against him...
Sunny was in heaven. He could hardly process a thing anymore. In and out, up and down, something both painful and good, feeling like he was being crushed, the occasional feeling of ejaculating, he was so happy. He loved this...he loved it so much...Mari...Hero....
Hero made a valiant effort holding out this long, but he had finally exhausted himself. He let out a huge load, even bigger than the last.
Mari looked down at Sunny. His eyes weren't focusing anymore, and a line of drool was going down his mouth. She giggled and started to lick it up, giving him another deep kiss. "I love you too, Sunny...hmmm...~"
...
...
They had clearly gone too far. A small wave of guilt flooded Hero as he put their clothes in the wash.
Sunny seemed beyond overstimulated. Parts of his body were twitching, namely his sticky penis. Mari had the incredible idea of cleaning it off with her mouth, wiping every last inch of it with her tongue, and any additional spurts he let out. Sunny's eyes looked blank as he let out strained moans.
She was so easily doing this with her little brother after being so embarrassed about doing things with him earlier tonight. When Hero came back, Sunny had fallen...more unconscious than asleep. Mari seemed to be running her fingers across his body, from his arms to his thighs. His chest and belly.
"Well...this was a night." Hero tried to say as he started taking off Mari's bedsheets.
"Hehe...we went a little overboard, didn't we?" Mari said, less shame in her voice than he would have liked.
Hero was about to say something, but...yeah, he did too. He really should have stopped them before they wentn too far...
"Is...I hope Sunny's going to be okay." Hero looked over at the boy, a sleepy yet satisfied smile on his face.
Mari ran her finger on his cheek. "He'll be fine, I'm sure of it. Maybe...we could even do this again?"
Ah, this was Hero's first test. "No." He said.
Mari shook slightly. "B-but, Sunny's-"
Hero gave a harsh glare. "No. We shouldn't have done this in the first place, this was a one time thing, PERIOD."
Mari looked a little upset, but she surrendered. "Okay...this had all probably been a bit too much for him, anyways."
After recommending Mari take a quick shower or bath, Hero put pajama's on Sunny and tucked him in under the covers.
When Mari got back in her nightdress, she walked over to check on Sunny. He had such a content smile on his face, she couldn't help but stroke his hair. "Mmm...ri...hheh...ro...." Sunny mumbled in his snoozing.
Mari grinned and whispered "Hero, he's the cutest..." Hero couldn't help but silently agree.
...
Hero couldn't stop himself form grinning. "M-Mari, seriously? They had been resting on the couch for 2 minutes, and she was already getting frisky.
Mari giggled, reaching a hand into his pajama pants. "We have the house to ourselves for a whole weekend, let's have some more fun!"
Hero responded by giving her a tight kiss. Mari tried to resist and keep her control, but Hero rolled her under him. Hehe, Hero~