Aislin is Alex's sister and she's kind of awesome. In addition to being a Keeper, Aislin is also a witch and can do super cool things like transport everyone magically using a crystal and some wild incantations:
"So… how exactly did we get to Nevada in just a split second's time?"
He hesitated. "Aislin transported us here." (15.58-59)
As a Keeper, Aislin uses her powers for good and is 100% committed to protecting Gemma and saving humanity. Aislin maintains loyalty toward Laylen, too, even though he's a vampire and has been shunned by the rest of the Keepers. She has a serious fondness for him and will stay and fight with him no matter what. In this, we see that loyalty is a key quality of Aislin's, though it remains to be seen in future books where her loyalties lie when it comes to her father, Stephan, and Gemma's soul.
Do you think the Keeper part of Aislin will lead her to follow Stephan's lead? Or will her sense of duty to protecting Gemma inspire her to stop Stephan from destroying Gemma's soul?