Okay, so my main character's name is Charlie and he has come into possession of a mysterious golden mask the gives mystical powers. The only way to access the power of the mask is to have a direct blood lineage to the original owner of the mask. The problem I'm having is developing a back story for him and making him likeable. So far I've established him as a drunken college student, but I need ideas to make him more interesting to pull the reader in. He really needs a reason to take on the role of this golden mask character and become a hero, but I'm just drawing a blank because every hero back story seems like it's been used.
He doesn't need to be likeable. Think of the film 'Hancock'. Early on he was a drunken layabout. Why is your MC a drunken college student? What is he studying? Why is he taking these subjects? Why does he drink? 'Direct blood lineage' you say. Okay, plenty of scope for a bit of miscegenation over the centuries. Is he mixed race? Is he hung up about it? The back story is all there if you flesh out what you've already told us, you just need to figure out what motivates him.
There's some saying about how every idea has already been used. Become comfortable with that and write what you want.
Define the history of the mask. Where did it come from, who forged it, for what purpose, why does the user need to have ancestral blood, and how did the bloodline fall and result in your MC's current circumstances? By defining the history of the mask and its relation to your MC's bloodline you'll come to refine your MC's history.
If you were him, what would it take for you to take on the role of being a hero? Maybe he plays with the powers for fun at first, but then he witnesses something tragic and decides to use the powers to help others. He can start small: plays around with powers, uses powers to get back or humiliate enemies/rivals, uses powers to help those close to him with their problems, uses powers to help strangers, etc. Interview your protagonist. What's important to him? What are his goals in life? How did he get this mask? What are his flaws and innermost thoughts? What are his strengths? How does this affect how he'll use this mask? I hope this helps some or at least gets you thinking. I know how difficult solidifying your ideas can be.