History
Marrow was a mutant prisoner in a sentinel detention facility where she was imprisoned, alongside Bishop, Domino, Firestar, and Hellion. Professor Xavier's meets her here, and son after escaped with Professor X and the rest of the team[1].
Marrow was with the team when they meet Polaris, who assembles a friendly Sentinel which the team leaves with. Marrow develops a friendship with the Sentinel which becomes named Rover[2].
Eventually, Marrow caused trouble for the team because of her attachment to Rover. She decides to have Rover help the team, but Rover ends up being destroyed. She decides then to tell a group of Sentinels that she could lead them to Charles Xavier[3], but later bring Polaris back with her to confront the Master Mold[4].Attributes
Powers
Seemingly those of Sarah Rushman (Earth-616)
Notes
She can be seen in the show's opening sequence for season one being held prisoner in an MRD vehicle. Voiced by Tara Strong.
Trivia
Marrow's appearance resembles to her mainstream counterpart after she had been healed by the Skrull healing machine, except that her bones have a more jagged appearance.