Board Thread:General Discussion/@comment-26006155-20190131130037/@comment-26006155-20190201172304

I forgot who exactly said it (was it Starscream?), but I have more of an answer for the argument that Asriel and Chara's souls must have fused together, and must both still be intact.

Asriel said that when he and Chara combined souls, they both had partial control. If he still had two souls within him after become a flower, he should still feel that familiar tug of war for control just as before.

That the tug of war is gone tells me that there's only one soul still in Flowey. And the complete unnatural lack of compassion, as well as the SAVE/LOAD ability, suggests this is Chara's soul.