Harry James Potter Evans Verre, the character we have followed for 104 chapters now is not and never has been Harry Potter. He is not the genetic offspring of James and Lily Potter. He is not canon Harry. He is, and always has been, Tom Riddle. He is not some amalgam of canon Harry and the Riddle Horcrux. He is 100% Riddle.
Quirrell is David Monroe. (Likely he’s been other people too, but Monroe is one of them.) Quirrell may also be Riddle, but I’m guessing not, or at least not fully. If there’s a partial Riddle who can speak Parseltongue (i.e. for the same reason as canon Harry can speak Parseltongue) then it is Monroe/Quirrell. Possibly Monroe and Riddle were both Lord Voldemort. Or Riddle/Voldemort was Monroe/Quirrell’s stalking horse. Or perhaps the diary comes into it somewhere, and HJPEV is just the diary come to life (a common event in HP fanfic) but either way, HJPEV is not Harry Potter.
I don’t have time to run back through 103 chapters to pull out all the evidence for this hypothesis before the next chapter is posted, but I do recall the sorting hat way back in Chapter 10:
I cannot and will not tell you about my conversation with the one who became the Dark Lord. I can only know, while speaking to you, a statistical summary of what I remember, a weighted average; I cannot reveal to you the inner secrets of any other child, just as I will never reveal yours. For the same reason, I can’t speculate on how you got the Dark Lord’s brother wand, since I cannot specifically know about the Dark Lord or any similarities between you. I can tell you that there is definitely nothing like a ghost – mind, intelligence, memory, personality, or feelings – in your scar. Otherwise it would be participating in this conversation, being under my brim.
and even more suggestive in Chapter 7:
“Cor,” said the red-haired boy, “are you really Harry Potter?”
Not this again. “I have no logical way of knowing that for certain. My parents raised me to believe that my name was Harry James Potter-Evans-Verres, and many people here have told me that I look like my parents, I mean my other parents, but,” Harry frowned, realising, “for all I know, there could easily be spells to polymorph a child into a specified appearance-“
HJPEV is one integrated personality, not two, and that personality is Tom Riddle.