Personality-wise, not too much. The differences aren't with Alena herself so much as what she deals with on a day to day basis. Probably the biggest difference between Alena in canon and Alena in aather is that Alena in Aather doesn't need to carry her issues around and is free to just participate in adventure after adventure. That and the fact she can spin them to be a positive or inspiring thing. ("Hey you think you have unsolvable problems? You just need to kick them down!")
The second biggest difference from Aather and her canon is that in canon, there's not a lot of moral/ethical dilemmas. Whereas in Aather that sort of thing happens every third game. |D

So in summary: Alena's personality is very similar to her canon's, but here she's dealing with separate issues and so different sides of her personality that normally don't come out can come out.