FLAYON<<

-As a child he formed a contract with Chibitrus to get out of his current living situation and they formed a pact where Flay became part android? (this part is not clear to me) and immortal. His age is how many times he has died which is why that fic described death as instant and fleeting. He also physically connects to the R-TRUS through his tail which is attached to his spine.
-His hair turning red is a consequence of this pact (unsure of what this means, my theory is that every time he dies it becomes more and more red) and that he basically lives inside the R-TRUS, the R-TRUS also has a conscience of its own so I guess you could say they act as partners.
-Declared himself as the "most likely to betray the guild"

-Knew Doppio Dropscythe from they were kids

R-TRUS<<

-Chibitrus is made of black goo (unknown substance) and the armor is holding him together in one piece

MACHIROONS<<

-Made of the same goo from Chibitrus, held together by the armor
-Used as fuel for the R-TRUS or energy for Flayon
-Manifested out of Flayon's positive/negative energy

[Not canon/theories]
-[npc question in /mans/]This is a tricky question because I think it might be heavily biased on who you watch, personally I think Axel given the way Altare meets him in the manga, and Bettel because his character has no substance for now. While Altare might be the only actual "human", I think Flayon on the other hand works with the corruption that is spreading through their world based on how he formed a pact with chibitrus and how he declared himself as the most likely to betray the guild after someone in chat talked about Magni being that
-Magni and Ves leaked that he's actually 2 people in one (assuming that means there's possession happening?) and that he was at some point in a cryostasis
-they probably mean the r-trus and flay, since they're linked together after they formed a pact and i'm not sure it's known the r-trus has a conscience. the cryostasis part is interesting, because it's unknown what happens to him after he dies, maybe it's a similar to what homura from madoka magica went through during timeloops, as in the more she experienced it the more she got used to the process