Sebastian isn't upset with Apollo or Cassandra; rather, he didn't think it wise to associate with people insulting the gods in their own temple. It's taken years and a lot of grief, but he's learned a measure of caution.

"Pleasure," he replies, accepting the handshake and hoping that Apollo isn't put off by the scarring and missing fingers. His knowledge of Greek mythology and proper Ancient Hellenic custom is pretty weak, but he knows enough that good manners are always welcome.