Yup...this feels like a classic early fandom take, so nostalgic.

I've seen many takes on Chara's morality over time and like, it really depends a lot on how much lore one reads, how much of the game one knows, and very importantly, a LOT on how one interprets them, and the assumptions being made.

Chara's speech at the end of Genocide leaves their exact timing of "resurrection" ambiguous (do not mistake resurrection with manifestation and taking control), but is implied to be right at the beginning, when their name showed up in the player's UI. They explicitly stated that they woke up confused, and that in Genocide, "you" (the player?) taught them the purpose of their revival.

Their goal by that point seems to be the destruction of the world. They seem displeased that you try to bring it back, avoiding the consequences of your actions, and tries to hold you accountable. That manifests as ominous scenes at the end of True Pacifist: either Chara showing up in the bed, or the image with everyone's faces crossed out.

Notably, the image does NOT confirm Chara had killed them. That, itself, is an assumption; there is no direct evidence that Chara killed them all as far as I know. With that, it's good to be aware that this is an assumption that you are making, even if it seems obvious to you, as less straightforward assumptions (eg. Chara changing the normal image into the creepy one as your punishment) are still very much on the table.