I have a headcanon to share about Chara!
So obviously as most know by now, if you do genocide and then a true pacifist run, then you get the soulless ending where chara is set free into the surface. I propose that staying with Toriel is the right choice in this event. My headcanon is that you're SUPPOSED to do genocide then true pacifist. Because you set Chara into your body then he/she/they are set free. At the end of true pacifist if you return then flowey shows up saying "hey, everything is perfect here. I know you can reset but why would you?" For both pacifist and tpacifist he points towards another ending. So what if he's tricking you into letting Chara into you via genocide. Considering Chara can destroy worlds, they're probably capable of bringing Asriel back. In which case then you choose to go with Toriel and Chara takes full control or it's kinda like yuji/sukuna where frisk and chara can switch and eventually they can make a new vessel. However if you chose to go, then Chara goes to harm those who harmed Asriel since Asriel was likely one of if not their only real friends.
Sorry for the yap. 😅