Personality
Some superheroes are ready for the fight. Others are drawn to the clash of fists. Then there are those like Healer. He is a 'practical pacifist', preferring to stay on the sidelines to help those injured in the aftermath of big brawls, preventing casualties as the big names crash through buildings and throw cars at each other. He has low self-esteem, but a big heart, looking to prevent any needless deaths. He has a bit of a sense of humor, sometimes at inappropriate times, but is not a quip-slinger. He leaves that to those who are good at it. If push comes to shove though, he will defend himself and others, but will even likely heal an enemy's injuries.
Background
Mark Matthews was born to Scott and Tricia Matthews, two middle-income parents. At an early age, Mark lost his father in a fire. Since then, Tricia has been extremely overprotective of him, and he has been extremely clingy towards her. At around 12 years old, he and his mom ended up in a car accident. He was mostly unharmed, but the same could not be said for his mother.
His mother was fatally wounded, and there was no chance of the ambulance arriving on time. In a panic, he held on tight to his mother, crying and shaking her, telling her to stay with him and begging her not to die. He could not lose both his parents. To both their surprise, this worked. Mark unlocked a powerful ability, healing his mother's injuries.
Tricia Matthews was both amazed and proud of her son, and worried about what others would think if they found out. She made him keep this a secret, claiming to have been miraculously uninjured in the collision, and told him to forget about it. In secret, over the years, he continued practicing and honing his powers, starting with small cuts and bruises from bullies picking on him, working his way up to learning how to heal serious injuries. By the time he was able to leave home, he had all but mastered his skill. He used it to overexert himself working out then healing himself faster to build himself up. He also had a mission - prevent the needless deaths of others, but as a superhero to protect his identity, getting a job as a website developer.