Little is known about Mephisto's past. His first name is Matthew, and he first appeared as he was taken under the tutorship of the same Dreamspeaker who was teaching Zatanna. Quickly a strong competition built between Zatanna and Mephisto, where Zatanna always managed to keep the upper hand over him. Mephisto eventually left. Next time he was "seen", he fought against his former mentor in what at first seemed to be an amical duel, but which quickly turned into a to-the-death match. Mephisto then killed the old Dreamspeaker.

During another encounter with Desmani, Mephisto succeeded in gaining his magical gauntlet, giving him control of a powerful demon. Mephisto used this demon for his own needs, sending him against Zatanna so he could finally take revenge for all the times she outsmarted him. The demon caught her unaware, and killed her.

Desmani was after him, trying to recover his gauntlet. At that time, Zatanna's apprentice also decided to track him down and avenge his mentor's murder. Mephisto laid down various traps, resulting in two encounters between the demon and Tim. The first time Tim and his friends were taken unaware, and fled for their life. The second time they managed to fight back the partial incarnation of the demon that was summoned by shielding themselve with one of the Nine Kids, which couldn't be harmed by the demon because they contained a part of Desmani's former Avatar. In the contract binding the demon to Desmani's gauntlet, it was stated that the demon couldn't in ANY way harm Desmani, or any part of him.

The Cabal then managed to track down the gauntlet, and finaly went on the offensive. Taken by surprise by the aggressivity of the Cabal (it was his first encounter face-to-face with them), Mephisto tried to flee so he could get more prepared, and summon the demon to his help. He was tracked down through the Umbra by Tim, then as he went back on the material plane it was Sky's turn to track him down. In that final showdown that involved most of Tim's Cabal, the return of Harold Cunningham (who couldn't be harmed by the demon either, as he was linked with one of the Nine Kids, so any harm done to him would pass to the kid hosting a parcel of Desmani's Avatar), the USS Missouri sent airborne by Sons of Ether mages, Men in Black alerted as Lain broadcasted throughout the world the whole event, and mages from the Order of Hermes. Mephisto succeeded in summoning the demon, but Harold went after the demon, which was forbidden from harming him. Sky emptied a bunch of guns in his guts, and succeeded in tearing off the gauntlet (and the whole arm) from him. Tim finished him with a bullet in the head.

Goals:

Mephisto's goals seemed to be revenge (against Zatanna), and a thirst for power. Not much more was known of his real agenda involved in the demon he controled through the artifact stolen from Desmani. It is also debated wether he was really controling the demon, or it was in fact Desmani controling him.