The Other Side

To be honest, I feel like dark Luke goes against who he is. Sure, he not a "true Jedi" in some ways (like attachment is important to him) but he's very pure-hearted. Even he did go to the Dark Side, I imagine he'd be the most mild Dark Side person there is (if that's possible). If anything, I think he'd be more gray, a balance between the light and dark side (in some ways, he already is). I'm actually far more interested in dark Leia. She's a lot like Anakin, including being filled with anger that she has trouble controlling. It's probably why Luke was so upset when Vader said that he'd have Leia join him, because Luke knew she wouldn't be able to resist the Dark Side like he could. I wouldn't mind a AU where the Sith train Leia and have her join the Dark Side.