N.B. Yes before your ask I've been playing with this character before. I've made some changes to him like a new username, new middle name and altered some background information. Even changing the nature of his powers. Let's see if I can keep my interest this time!
Basics
Name: Liam Matthew Harper
Fandom: Original; inspired my Marvel and X-men. Fandom OC? Possibly if I knew enough of Marvel to make it work.
Age: 18-ish
Nationality: American
Species: Human/Mutant
Bio
Liam's a middle child. His brother John is 7 years older than him. Liam also have a baby sister by the name of May. She's only about 2. His childhood was a normal one without much of note. As he entered his teens he took up boxing and he was pretty good at it, even won a local junior league.
Liam's mutant powers showed late in his teens. It took him by surprise. Without any proper training he has been struggling somewhat. However he's actually pretty happy about it. Growing up he was always interested in superhero comics and mysterious vigilantes making a change. However the discovery of these powers came to a high price. His family feared him. To them he was an abomination and it didn't take long before he found himself thrown out of his house at the tender age of 16. Life would prove to be difficult from there.
Eventually he turned up in New York without many dollars to his name, trying to make living and perhaps fulfil some of his childhood fantasies. However the missing training is a rather big issue and he struggles with his control. Which makes life even more complicated.
As for rolemodels he does look up to Captain America.
Around 18-19 he was accepted at the Xavier Institution/Jean Grey's School for Gifted Individuals. (This depends a lot on canon point for other Marvel muses he interacts with).
Personality
Laid back, easy going, a bit naive and somewhat of a dreamer. He has some issues with impulse control because of his rather young age. He's practical and not particularly good at more theoretical work. He enjoys working with his hands a lot and has an interest for geology, which might be due to his mutation.
However he's also a broken soul. Getting throw out have left deep scars which makes him scared of relationships. He doesn't want to go through the pain of losing his stability again.
Appearance

Liam is blond with blue eyes. He looks young and have a shyness to his body language. He doesn't have any obvious marks or scars on his body. He has the physique of a light-weight boxer. His physique is additionally augmented by the X-gene making him look very toned. It also means he's slightly heavier for someone only being 5'9".
He's usually clean-shaved.
He prefers single colored t-shirts and slightly worn jeans.
Powers
Geokinetic powers. Earth-focused. He has the ability to manipulate earthly materials like rocks, sand and dirt. He can cover himself completely or partially in a hardened shell of rock and/or weapons. He can also cause the surrounding area to shatter, lower or raise as long it's made of earthly materials. He can also summon forth and/or levitate chunks of rock. He can't manipulate iron or other man-made materials (not including asphalt or concrete however things like plastic or steel is out of his reach). He needs to be grounded to use his powers.