Mark was born to Dyson and another shifter named Piper. He grew up without his father, who did not know when he and Piper separated that she was pregnant. He also spent much of his life on the run, after a man known as The Hunter murdered his mother and began chasing Mark down as well.
Mark encountered Bo and Tamsin after witnessing The Hunter kill a young woman mistakenly when he was aiming for Mark. At first he seems simply scared and hapless, but it's soon revealed that Mark has a deceptive and manipulative streak. He plays upon Bo's sympathies and then robs her before running away. When Bo and Tamsin track him down he confesses the truth about The Hunter that's chasing him, just before Bo is shot with an arrow by The Hunter.
Mark is eventually rescued from The Hunter and the truth about his parentage is revealed, but not before he and Bo had sex and she afterwards realized, aghast, that her attraction was due to his relation to Dyson.
Mark begins working at The Dal and is soon befriended by Vex. Vex and Mark manage to get into a bar fight which results in Dyson being called. Dyson warns Vex to stay away from his son, an order that Vex doesn't seem to take too seriously as he continues to spend time with Mark at the tavern. The two eventually form a friendship which becomes romantic (Rise).
Mark also becomes friends, and romantically entangled, with Iris. They bond over their mutual frustration with their parents, but the relationship ends in tragedy when Mark is nearly killed due to Iris's accidental murder of the father of her host body.
Unlike Dyson, who shifts into a wolf, Mark shifts into a panther. He has not gone through the The Dawning and has refused to align with either the Light or Dark clan. Like Bo, he remained unaligned.
Mark's sexual orientation is bisexual; having shown sexual interest for both females (Bo and Iris) and males (Vex).
He is at times cocky, impulsive, and rebellious.
Mark is good at playing on people's sympathy to get what he wants.
He is strong-willed and stubborn, with a mischievous and fun-loving streak as well.
- Dyson: His father. Mark did not know Dyson was his father until he was a teenager; and Dyson was not aware of Mark's existence until such time. He has an uneasy relationship with Dyson that results in his acting out around him. Although their relationship is strained they eventually come to an understanding and grow close, with Dyson seeming to support both Mark's decision to remain unaligned and his relationship with Vex.
- Piper: His mother. She was murdered by The Hunter when Mark was six years old.
- Vex: His boyfriend. Initially friends after Mark began working at The Dal, their relationship progressed to romantic. They remained together (Rise).