Well, nothing to lose but my dignity, and that went out the window years ago...
Mage is a Dark-type Trainer. Not even one of those "Darkness is misunderstood" Dark-type trainers. He's psychotic. His solitary nature and tortured past have left a deep-seated anger in his soul and a large amount of angst that has lasted well past his teen years. Though he is more than a little unbalanced, he has a good heart beneath all that pain.
His gym is as foreboding as it is stereotypical, sporting an imposing keep and a stadium that best resembles an old-fashioned dungeon(complete with a few fake skeletons tossed around for good measure). His actual living space isn't quite as macabre, but few ever get to see that. Mostly they see the grand entrance hall, which would make Bram Stoker(not to mention Vlad the Impaler himself) rather proud.
His pokemon are often his only friends. Though they like to cause a fair bit of mischief, they're about as truly evil as their Trainer. Mage's battle style is brutal, but effective, often relying on skills that are a little off-element(though he does know a few fun dark-type tricks). His signature move is called Mind Breaker, and is basically a Dark-type version of Psychic(Power 90, AC 100, PP 10, 25% chance of lowering Sp. DEF 1 level). His favorite pokemon, if you had to twist his arm on it, is his Murkrow. He's not fun to cross, but he fights fair and hates those who don't. He's deeply loyal to those he trusts, and will defend them at all personal costs.
Physically, Mage is of an average height and slightly heavy build, with a face you'd soon forget and really dark brown hair. He typically dresses in a rebel-biker style, with blue-jeans, T-shirts, and a simple black jacket in cold weather. His boots are steel-toed, and he wears thick, squarish, silver-rimmed glasses. Although he often feels he's alone, when things are really at their worst there are a lot who would stand behind him.
Hope you managed to get through all that. I tried to keep it brief.
EDIT:
Real Name: Concealed for security purposes
Alias: Lord Mage
Badge: Dark Eye Badge
Gym Type: Dark
Lineup: Houndoom(Level 29), Murkrow(Level 31), Umbreon(Level 29), Sableye(Level 30)