I don't find either of the companions particularly evil, at all.

I mean Astarion is a Vampire, so yeah, he sure as hell isn't good, but he is cliche and and can go either way (figuratively and literally), but the rest are all self centered perhaps, but Evil? THey might be more relaxed with the player being of dubious morals, but not even Shadowheart strikes me as particularly evil and she worships Shar. I mean I played what I determined as CHaotic Good, with a touch of Sod you murderhobo if someone really ticked me off and I was universally loved by my party. Well I think Laezel might have only been moderatly enamoured.

Maybe Larian needs to hire Claudia Black for some voiceovers, always liked her dubious characters in games. lol.

I'm certain it's why we have seen calls for the Drow to be able to join us rather than betray us.