I think it is possible. Bioware just need to create a NPC that you can customize and choose if they are evil or good and have him/her run around the ship and you have to get gifts from different planets in order to get affection and certain points have a chat with him/her with some involving your spouse.

Malgus > Revan > Malak. Malgus is a pure sith all the way. All have there ups and downs but overall Malgus is my favourite.