Board Thread:Questions and Answers/@comment-27524978-20160114233341/@comment-27560522-20160116063105

He's still Asriel, and he retains all of Asriel's memories.

In Geno, he mentions to Chara how he thought his parents could help him regain the ability to feel positive emotions, but both of them failed - so that seems to prove he knows who his parents are. He's just unable to care about them in that state... killing them comes off as nothing to him. He pretty much doesn't view the denizens of the underground as people anymore - they're just playthings for his game of reset.

Despite being unable to feel positive emotions - he's still very much able to feel negative ones.

He mentions he cried for a long time the first time he became a flower, so he can feel sadness. He clearly feels fear once he meets the real Chara and realizes they will kill him - so he can feel that too...and he cries again in that ending as well. And then there's anger, too, boy, that is one angry flower.

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We can't truly imagine what it would be like to be an immortal limbless creature incapable of feeling love, compassion, etc. Flowey/Asriel's just been driven insane by being stuck for who knows how long in that pitiful state.