I get very different impressions from Cass and Cassandra. Cass I find to be down-to-earth, tomboyish and realistic while Cassandra is fluffy, maybe a bit of an airhead and very girly. Altogether I see this girl having a feminine "airy" name but is trying to live it down by having a more boyish nickname.
Dorian I see as quite a shy boy but underneath he has a big personality, I'm not sure what to make of the Hunter because normally it gives me negative associations but together with Dorian I get the feeling of a mixed personality - maybe a shy male who has bursts of anger often.
I have never come across the name Liadan so it's quite difficult for me to give an impression, but from just looking at the name and sounding it out I would think this character is warm and friendly, a little shy but with a cute smile that she definitely doesn't show often enough.
Hope this has helped somewhat :)