Fauxtroject. Bullshit term by Imia.
Faux + Introject. I specifically made this to describe my experience of "absorbing" a character into my being & identity, while not being an "original" introject source that I was formed with. These fauxtrojects are often something I have heavily latched on to, and feel as if I cannot separate from myself. There's no real distinction between them (beyond not forming with them) in my personal experience. Anyone can use this if they want & feel free to tweak it to your liking!