Marcus may be seems kind, harmless and friendly, but his act of innocence doesn't fool Leo. He reveals himself to be a truly dark character, a ruthless, manipulative liar, who will not let Leo to interfere with his plans, and will stop at nothing to achieve his goals. Despite this, he can create a believeable facade of being a friend. He only reveals his true personallity to Leo, as no one believes him. Leo seems to be the only one that can see his true self, this is most likely due to the fact Leo disliked and suspect him since in S1E19 Concert in a Can before he found out he was evil and bionic because of his dad. Marcus has a complicated relationship with his "father", who is Donald's evil brother, Douglas Davenport, .
- Marcus is Michael Thorndyke and Leo's arch enemy.
- Jeffrey and Jaden will face Marcus one day in the future.