You first meet Karyl in Moreau when you are searching for Bastista. He helps you escape the guards that chase you by scaring them away with his music. He then asks you to help him break into the castle and save his friend and his friend's wife. You agree, since Bastista is up there as well.
[Personality]
Karyl is a wandering minstrel, even though he is from the great aristocratic Sheeden family. He's kind of weird, but you can always sense something deep about him when he talks.
I never really used Karyl in battle, but his attacks and defense seem decent.
[The Truth]
Warning! This section explains nearly everything about Karyl. If you don't want to know, then don't read!