Board Thread:General Discussion/@comment-27573099-20160304020037/@comment-27047700-20160313225513

Doubt it, Chara is a completely different person. Chara is the first human, while Frisk is the eighth. Chara was awoken because of Frisk's DETERMINATION. Then, Chara possessed Frisk in a Genocide run, hence why Frisk brutally killed Asgore and Flowey. My theory of why you cannot complete True Pacifist after Genocide is that Chara has awoken in every run after Genocide (Since Chara awoke in Genocide, allowing her to be awake in other runs), allowing Chara to possess Frisk whenever she wants.

Saying that Frisk has gone crazy is a little farfetched, but hey, that's just my opinion. You could be right, but this is what I think.