He and Callum keep trading insults and try and one-up eachother, it's just not worth it...Callum will hang himself as he keeps banging on about Dexter.
Dexter should hang around with Gina, have a laugh with her and spend time with the others, and he shouldn't even pass a comment about the loony.
Callum's smug little mad eyed face lights up everytime Dexter chats to him, Callum is waiting for what he thinks will be a wrong comment from Dexter and then Callum will repeat what was said to the world...many, many times.
Dexter is better than this and should keep away...let Callum slowly go insane by himself.