Are you like a valley girl like?
Let's see if I can translate: You are wondering if as a dark side jedi knight character, can you romance Kira. You are concerned because the Imperial companions Vette and Ashara generally prefer LS decisions and so does Kira.
Suffice it to say, in all cases, regardless of LS/DS choices you can romance a companion. It may take a lot of companion gifts to compensate for those companions not liking the decisions you make, but gifts are a cure all.