Okay I want to make my character dark but I don't want to go to far. He starts out as a wimp whose always at the mercy of people(mobsters) more powerful than him. However as he discovers his family legacy and slowly begins rebuilding it he becomes stronger and fiercer and when the mobsters from his past come at them he starts getting scarred but then he orders his own people to slaughter them without leaving any survivors. Essentially it goes down like this but I worry it makes him to dark what do you think?
Characters can have a dark side and still be usable. Look at Dr Who for example: while the Doctor is kind and compassionate, he also has a very dark side-one that has committed genocide several times to either protect the universe of stop a hostile race that wouldn't take the chance at a peaceful solution he gives them. On the other hand, he also comes down hard on those who commit genocide too. The PM in 'The Christmas Invasion' and 'Solomon' from 'Dinosaurs on a Spaceship' come to mind. My MC ends up, and it's a shame she will always carry with her, committing genocide against a race the orchestrated the murder of her race by a third party, then the same bad guys committed genocide on a second race and wanted to make mankind the third. They refused a peaceful offer and it left no option. However, keep in mind anytime a person-even a fictional one-is killed, there are moral consequences to the person who commits the act unless they're a sociopath.
It probably says something about me that I first thought of Alucard from Hellsing Abridged than the actual OVA. Maybe cause he's funnier. Anyhow, you know the saying about the brightest lights cast the deepest of shadows? Well, consider an alternative take: a fire flickers and smolders, and its light varies from bright to dim. The shadows it casts vary likewise. A multifaceted character will naturally have some elements of darkness to them...whether it be mundane ("Bro, if you don't shut up, I'm gonna smack you," he muttered dangerously.) or horrifying (hello there Hitler!) or somewhere in between ("Yes, I'm a professional clown.").
I forget who said it, I think it was Dumbledor or someone of the like, but they said something along the lines of "the world is not divided between light and dark, the world is grey." There are a lot of characters that fall into the category of grey, Doctor Who being one of the more well known ones. You're character can definitely be grey, while holding that edge of darkness. I noticed you referenced an anime, are you a fan of anime? If so, I'm sure you'll notice that in a lot of animes, there are a lot of characters that can be rather dark, but never go too far. Alucard is actually one of those characters. As for worrying if your character is too dark, try not to think of him as being "dark". Labelling him as such will only cloud how you represent us to him. Most times when people hear the word "dark" in relation to a person they'll think of someone evil, mysterious, or even a killer. Try finding other terms that'll suit him, without clouding your own judgement of him too much. If need be, try reading a lot of books, or watching things, where the character represents your own. There's a ton of examples out there, and they're all at your disposal.
It sounds to me very like the bit from The Usual Suspects where they are discussing the legend that is keyser soze. WARNING CONTAINS GRAFIC CONTENT IT IS ADVISED YOU SHOULD NOT WATCH THIS IF YOUR SQEAMISH OR UNDER THE AGE OF 18. http://www.youtube.com/watch?v=BgkBpWc8ngI That is one dark sob.
