So all that Asriel wants, once he's remembered that he's Asriel again and not merely a mutant flower, is play with Chara, and they want this so badly they see Frisk as Chara. But then Asriel starts remembering what playing with Chara was like, both the good and the bad...the good was, playing with Chara was the only time that Asriel could really and truly remember being happy...the bad was that not once did Chara ever let them _win_.

*sighs*

I know what it's like, not to want to lose. What's more...I know what it's like to know that you can browbeat someone weaker than you into "losing" to you. #Undertale