About that smirk...(spoilers)

[SpookRooster]

Here's a boring answer:

She's not evil because you can play Triple Triad with her. Evil characters can't be interacted with normally and you'd lose a shot at getting her rare cards if she betrayed you.

But there's a Nidhogg card...and Bahamut. Wait...you mean play the game with her. When can you do that?