The most toxic survivor lorewise?

Ace, David, and Nea all come to mind. The playboy gambler, the borderline sociopathic fight-enthusiast, and the vandal.

Depends on what you define as toxic. Because being toxic lorewise is definitely not the same as being toxic gameplay wise it's not going to be clicking flashlights and throwing butt dances at a trapper in lore

Min being a lone wolf doesn't care about the other survivors and would leave them injured or to die prioritising what she's doing over helping them. Even if helping them poses no threat to her. Also she comes across as the closest thing I would come to actively arrogant when it comes to survivors for example one of her quote is literally U mad

I don't blame her if people kept getting my name wrong I'd be toxic too