Wait so your theory is that MC's first Esper who died with a hole in his chest, got reincarnated into the MLs body when he was 19yo and that's why he's now sticking so closely to the old body MC?
The "please don't hate me" did sound off, I wonder if there's a reason for that specific line or if this is actually a mistranslation. I can understand him sticking to the one person who actually helped him and made a very responsible and steadfast impression. No one else is at a high enough level to guide him so he probably didn't get an alternative role model either.
Right now I don't have the impression that his first Esper was reincarnated though.
I am just guessing but I think both of them came back, like he said his family and partner died that day so maybe it was also possible for him too???
Bro meets him once and already is blushing I just know that doesn’t make sense( ̄へ ̄)