I don't think alignments are necessary to answer that question. Just good writing. As it is, the characters seem consistent as it is. If you feel like it, you can pretend that they have alignments based on how they act, but in my opinion, as I already mentioned, I feel alignments are incredibly arbitrary. I don't think video games are a good medium for them, because developers might have different opinions on what makes an act belong to a particular alignment than a player would.
I get that people have different ideological interpretations of what is 'good' and what is not. But what 'good' characters would have in common would be a sense of individual dignity and rights, and of pursuing the common good. There are many possible ideological variations ; but this much in common.
