User blog comment:Modernmyrmidon/PE Proposal: Chara/@comment-26277897-20191116233925

Chara's motives are very ambiguous in general; while they are confirmed to hate humanity and had a plan that involved killing humanity off, how do you know that their reason for the plan was solely due to hatred? Perhaps they wanted to do so because they believed it was necessary for the monsters to live happily on the surface, in which case they'd be an anti-villain. It's also not confirmed whether Chara valued the Dreemurrs or not; their actions in the Genocide Route may not be reflective of how they viewed them in the past, and it is possible that they did truly love the Dreemurrs while they were alive, but Asriel's choice was perceived as a betrayal that also resulted in them permanently dying, hence why they're hateful towards the monsters. There also may be reason to believe that Chara might've also been present in the Pacifist Route, in which case they would've also been assisting Frisk and the Anomaly in that route as well.

Long story short, Chara being sympathetic or pure evil are both viable interpretations, so they can't be definitively called pure evil.