Costa is an extremely strong-willed and focused detective. He will do whatever it takes to achieve his goals, whether it’s tracking down the bad guys or saving loved ones from vampires. He does have a magnetic, almost intimidating charm that is hard to ignore, and comes in handy when interrogating people. Once he has put his mind to something, it is almost impossible to get him off the hunt.
Like Jeromos, he is brave and meets challenges head-on, but he can also be reckless. But he is hardly careless, and goes by instinct and intuition. He seems to be able to anticipate and read people’s minds. He feels he has to, as a cop. He is hardened and often jaded and sarcastic and sometimes appears unmoved, but he does have a soft spot for protecting those who need it. He is trustworthy and faithful, and will follow anyone he respects to the ends of the Earth, even Cameron, who he gets along with. He will stand by allies, even if they turn evil, and will try to get them to change.
However, he is extremely possessive and jealous, especially with the author Ms Price. The possessiveness comes from his wanting to protect her from the Vampire Guardian Angels and his frustration at her stubbornness to remain independent. He is very sensitive too and they often argue, which leads to clashes and the silent treatment from her. Ms Price feels he is too domineering and worried, and that he wants things done his way which clashes with her independent nature. But he is well-meaning and does his best to watch over her, although he knows he has met his match in Ms Price, who is equally strong-willed.
Note: In issue 3 and 5, Costa smokes cigarettes (kind of a film-noir look). But in Issue 6, he's kicked the habit. He's also cut his hair to an army look in Issue 6.