Well, I've been thinking about a cast and admittedly I haven't come up with much. However, I have decided that no matter what anyone says about age discrepancies, Johnny Depp will always be my Swallow! For me, he'd be perfect. Pity he isn't just a little (OK, just a lot) younger.
As for Domick, I just had a random thought. You know that guy in the video for 'Call Me When You're Sober'? I think he would be a great Domick. Dark and mysterious (although a little less drunk for Domick, I think). This is the only photo I could find, and he looks a little possessed, but I'm sure you'll see what I mean.