Warning: spoilers for anime-only fans!
Drake's major feature in the story so far is his loyalty to the Marines. He's also a serious and steady guy.
It's always very important to consider the backstory of each character to keep them IC while writing. Drake is a child of physical and emotional abuse that was deprived of his dream early on in his life, forced into piracy and eventually got the chance to join the Marines.
He's so loyal to them that he accepted an undercover mission, pretending to betray what he values the most in this world for their sake.
This is why he would not choose his s/o over the Marines, at least not without a struggle that'd tear him apart. It was already shown that he would face dishonour, torture and death before betraying his allegiance.
At the same time, this would make him a faithful lover because when he loves, he loves for real.
Drake is also very patient and attentive to the need of the people he cares about.
Despite his unshaken demeanour though, he's not immune to a little goofiness once in a while. He literally fainted with a bleeding nose once, which makes him easily flustered, although it's not clear what his weakness is – while the fandom (and Hawkins) assumed it was because of female nudity, it's left ambiguous in the manga.
He has a solid integrity but has no problem turning violent if his mission requires him too, even against weaker opponent (he's the one that destroyed Amigasa village in Wano).
As a last note, don't forget that Drake is biiiig (bigger and older than Kid, actually).
