Season 1, episode 5

"Speed and Spyke"

When Quicksilver steals from lockers at his high school, he sets up his classmate and long-time rival Evan Daniels (aka Spyke) to take the blame. Spyke is released from jail by Xavier and joins the X-Men. When the two meet again, Quicksilver boasts about getting away with his crimes but, unbeknownst to him, Spyke has taped the conversation. With the help of Cyclops and Jean, Spyke finally pins Quicksilver down (literally) and leaves him and his taped confession for the police. Quicksilver is sent to jail, but is broken out by Magneto. A previous relationship between the two is established but not elaborated on.

Season 1, episode 6

"Middleverse"

Brief cameo.

Season 1, episode 9

"Survival of the Fittest"

The Brotherhood and X-Men go head to head at a survival camp, but must work together to save Xavier and Mystique from Juggernaut when he is freed from his maximum security prison.

Season 1, episode 10

"Shadowed Past"

Quicksilver delivers a secret letter to Nightcrawler on Mystique's behalf, but passes on the information to Magneto. Ladies and gentlemen, we have a grass.

Season 1, episode 12

"The Cauldron (Part 1)"

Magneto gathers the world's most powerful mutants on Asteroid M.

Season 1, episode 13

"The Cauldron (Part 2)"

When Asteroid M is destroyed, two escape pods are seen leaving which are presumed to contain Magneto and Mystique. Quicksilver is notably absent from the Brotherhood members who escaped with the X-Men.

Season 2, episode 1

"Growing Pains"

The now leaderless Brotherhood are back in Bayville and they decide to go public with their powers at a school soccer game.

Season 2, episode 3

"Bada-Bing Bada-Boom!"

Appears in a brief scene complaining about the state of the boarding house.

Season 2, episode 9

"Joyride"

Mocks Avalanche for joining the X-Men.

Season 2, episode 13

"Shadow Dance"

Shows up at the school dance with four girls. All he's missing is a diamond-topped cane.

Season 2, episode 15

"The HeX Factor"

Mystique returns to the Brotherhood, bringing with her the Scarlet Witch whom she has freed from a psychiatric institution. A series of flashbacks show Magneto with a young Pietro leaving Wanda there years before.

Season 2, episode 16

"Day of Reckoning (Part 1)"

Xavier brings in the Brotherhood to work alongside the X-Men as they try to find Magneto.

Season 2, episode 17

"Day of Reckoning (Part 2)"

When the X-Men and the Brotherhood locate Magneto they find they have been set up. Quicksilver has betrayed them and he takes his place alongside his father. During the battle that ensues, Magneto appears to be crushed by a falling Sentinel. It is revealed that the 'Xavier' who led the teams into the battle was in fact Mystique.

Season 3, episode 1

"Day of Recovery"

It's revealed that Quicksilver saved Magneto from the falling Sentinel.

Season 3, episode 2

"The Stuff of Heroes"

Seen briefly with Magneto, Colossus and Gambit.

Season 3, episode 4

"The Stuff of Villains"

The Scarlet Witch traps Quicksilver as bait to find Magneto, but the Brotherhood are sent to rescue him. They are then less than thrilled when Magneto appoints Quicksilver as their new leader.

Season 3, episode 7

"The Toad, the Witch and the Wardrobe"

Quicksilver takes full advantage of his position as team leader, making the Brotherhood wait on him hand and foot.

Season 3, episode 12

"Dark Horizon (Part 1)"

Rogue, under the control of Mesmero, absorbs the powers of the X-Men, Brotherhood and Acolytes.

Season 3, episode 13

"Dark Horizon (Part 2)"

The three teams join forces to prevent the release of Apocalypse from his tomb. They are not successful.

Season 4, episode 1

"Impact"

Mystique, who was turned to stone when used as a key to free Apocalypse, is returned to the Brotherhood when Xavier cannot find a way to change her back.

Season 4, episode 2

"No Good Deed"

When Wanda accidentally causes a crash on the subway, the Brotherhood escape from the wreckage, inadvertantly leaving a path open for the other passengers. They are mistakenly hailed as heroes and, with fame and fortune beckoning, they begin deliberately causing accidents so that they can show up and save the day. When a staged accident goes awry, their scheme is exposed.

Season 4, episode 8

"Ascension (Part 1)"

The Brotherhood are asked to join the fight against Apocalypse. All but Wanda refuse.

Season 4, episode 9

"Ascension (Part 2)"

The rest of the Brotherhood have a change of heart and join the battle. With all the heroes working together, Apocalypse is defeated.