If Frisk spares him after the Omega Flowey fight, Flowey cries that he doesn't 'understand why they are being so nice to him' and runs away. He tries to lock Frisk into an unending battle because he wants to stay with them forever, as he's scared of being alone and he feels like Frisk is the only person who's fun to play with. Flowey mistakes Frisk at various points for his old dead best friend. During the game, Flowey (Asriel) follows Frisk around. Since Asriel and Flowey are the same person, he is the character Frisk meets at the start and the last character Frisk fights at the end. Of all the characters in Undertale, Asriel is the one who knows about Frisk's power to reset from the beginning.
