Have to look and act human? Aw, that puts somewhat of a pin in my plans. Perhaps I can work around it. How about human in a really impressive suit of armor that makes it [i]look[/i] somewhat monstrous? Try this on for size.

Human Bio:
[b]Name:[/b] Gregory King
[b]Age:[/b] 17
[b]Gender:[/b] Male
[b]Appearance:[/b] 5'11, 155 pounds, with an average build. His curly, sand-colored hair crowns a face with a sharp chin. Thin lips, big nose, thick eyebrows, persistent stubble, and bright brown eyes. He has an unusual quantity of body hair, which his popular summertime choice of attire (a yellow-striped green t-shirt and dark tan cargo shorts) tend to reveal.
[b]Personality:[/b] Gregory is the 'straight man'. He is considerate of others, helpful to strangers, and a joy to friends. He is also painfully moral, never cheating, doing drugs, being mean or manipulative, or having affairs, and Greg is openly critical of those who do. He'll never commit a crime or betray a friend. Though gullible and possessed of a tendency to miss obvious things, he's very intelligent and creative. Despite having a short temper and generally being impatient, he is also quick to forgive and tolerant of the faults of others. He's not particularly gifted socially, but high self-esteem and a knack for quick humor generally get him through. Those that truly annoy him or antagonize him, either with stupidity or cruelty, receive biting sarcasm. When it comes to the ladies, Greg is friendly and even playful on occasion, but it's obvious that relationships take second stage to his academic success. And kickboxing hobby. And work.
[b]Backstory:[/b] Greg was an energetic and imaginative child, fond of make-believe games with friends. He quickly emerged as the leader among other children, and by dealing with the cruelties of children he developed his heroic, steadfast nature. Those qualities stuck with him as he progressed through school with excellent grades, maintaining a small group of companions and ranking his way through a kickboxing class over the years. Aside from getting a job and becoming an avid driver, nothing much of significance distinguishes him from other highschool guys.
Skills: Gregory is strong, fairly quick, and smart all in one. A veritable jack-of-all-trades
[b]Alter Ego:[/b] Ironclad

Alter Ego Bio:
[b]Name:[/b] Ironclad 
[b]Gender:[/b] Male
[b]Appearance:[/b] A daunting suit of armor defines him; whether or not there is someone inside that metal coat matters not.
[hider=Ironclad][IMG]http://i59.tinypic.com/2dt9oo1.jpg[/IMG][/hider]
[b]Personality:[/b] Ironclad is everything Gregory is not; whereas the boy is hospitable, his Alter Ego is troublesome. While Greg withstands conflict, Ironclad seeks it. Human tact and rationality is replaced by an iron will and nerves of steel. This warrior spirit is quick to pick a fight and brutal to its enemies. Additionally, Ironclad is somewhat of a bully. Even among friends' egos Ironclad can be cantankerous and unpleasant, always trying to hurt someone mentally if not physically. These traits make Ironclad seem heartless and cruel—a monster.

However, Ironclad isn't entirely a battle-craving brawler. He's also somewhat accepting deep within, and can make steadfast allies or even get along with a foe that surrendered to him. His confidence rivals his loyalty in terms of strength, and despite his intimidating appearance he can be rather humorous. When fighting without any of his weapons -which is rare- Ironclad uses a distinctive kickboxing style. Finally, he talks with an exaggerated version of Greg's own Australian accent.
[b]Weapon(s):[/b] First, Ironclad's natural weapons. From sheathes on his wrists he can extend thin, foot-long blades, double-edged and straight, useful only for stabbing or blocking. Vicious curved metal claws rest on automated hinges on his wrists as well; while normally harmlessly folded back against his arms, these claws can snap forward into attack mode to deal severe close-range damage. Lastly is the scythe-blade on Ironclad's false tail, which is best used for disarming or disorienting an opponent. In addition to his natural weapons, Ironclad wields two sabres with adaptable hilts. As such, these weapons can be interlocked to form a staff sword or a Zweihänder. 
[b]Abilities:[/b] Ironclad is a master of any and all sword styles. Be it conventional, dual-wield, Florentine, Zweihänder, staff sword, or even pincer, Ironclad can use and abuse it. His armored body is also incredibly durable, with the only notable weak points being the slits on his chest and head as well as his eyes. An additional ability is his ability to project metal prongs from all over his armor, turning him into a spiked menace.