Deathstroke (Patreon)

For such a popular character, this guy's sure been mishandled. Because he's a badass, and has a cool costume, he gets thrown into whatever villain role DC can fit him into, from a lovelorn crazy man with a grudge against Green Arrow to Ra's al Ghul's treacherous right-hand-man to God only knows who he'll be in The Batman. And in the comics, he veers wildly from an all-out hero to a frickin' war criminal who nuked an entire city! Admittedly, he's scummy enough for his most famous story to involve him committing statutory rape, but still. What's the thesis of the character? What's his core?

Me, I'd do him as a cross between Mike from Breaking Bad and Boda Fett from you know where. He's a mercenary. That's it. For a while, he had a grudge against the Titans because he held them responsible for the death of his son, but he gave that up. Now he gets hired to do jobs, whether it's distracting Batman so Two-Face can rob a bank, hunting down the Joker for a bounty, or assassinating a foreign dignitary. 

He's not a good guy, but he does have a code of honor: keeping collateral damage down, only involving people who are 'in the business,' no women, no kids, that kinda thing. He's still a scumbag criminal, but as a rule he won't murder superheroes, as that's just going to bring the entire community down on his head. Bad for business. This makes for more interesting stories, as you can write him working with the bad guys if they pay his fee, the good guys if they pay his fee, whatever. But he's not out to take over the world or make the planet safe for democracy or anything.