Captain Skull is a stern, serious, and menacing inkling.  He's known to not give mercy but can be understandable if you get on his good side, though its very rare.  Many people have known Captain Skull as someone who should under any circumstances not be messed with.  Even though he is very threatening looking he can be soft and very respectful, but it's very rare and he's usually not so open about his emotions.  Everyone he's known has only been able to see his cold demeanor.