Today's Fact
Verified against two independent sources. Issues cited below.
The most loyal X-Man once walked out of the mansion behind its oldest enemy. Piotr Rasputin's little sister Illyana — Magik — had become an early victim of the Legacy Virus, the plague engineered to kill mutants through their own genetic code. Her death in 1993 landed on a man already carrying the loss of his parents and a head injury that had left him locked in his armoured shape, unable even to feel his dying sister's hug properly.
At Illyana's memorial service, Magneto arrived at the school openly recruiting for his Acolytes, offering a harder answer than Professor Xavier's dream of peaceful coexistence. In Uncanny X-Men #304 (1993), part of the Fatal Attractions crossover, Piotr made his choice in front of everyone: when the X-Men powered up Bishop for a strike against Magneto, Colossus attacked Bishop instead — and departed for the orbital sanctuary Avalon at Magneto's side.
He was no zealot once he got there. Piotr stayed with the Acolytes hoping his years under Xavier might soften their extremist methods from inside, and the experiment ended for him when Avalon fell and a brain-dead Magneto could no longer hold the cause together. Colossus drifted on to Excalibur in England, and only much later rebuilt his friendships with the teammates he had struck on his way out.
Why It's Obscure
Grief did what no villain ever managed: it moved the X-Men's gentlest strongman into Magneto's ranks, at a funeral, in front of the whole family.
Gallery
Comic art of Colossus in his organic steel form — the armoured shape shown in full in both Colossus images — plus art of Magneto, the man he followed to Avalon. No AI imagery, nothing mislabeled.



Sources
Every claim above is verified against at least two of these independent sources.
Bullpen Bulletins
- Why Colossus Quit the X-Men and Joined Magneto's Acolytes — CBRStates that Illyana's death from the Legacy Virus, coupled with a brain injury that trapped him in armoured form, led Colossus to leave the X-Men in Uncanny X-Men #304 and join the Acolytes at her funeral.
- The Crimes of Colossus — Marvel.comMarvel's own account: after Illyana died of the Legacy Virus, Colossus turned his back on Xavier and joined Magneto's Acolytes, later leaving when he could not agree with their actions.
- Colossus Biography — UncannyXMen.netDetails the memorial service in Uncanny X-Men #303-304: Magneto recruiting, Piotr attacking Bishop, and his departure to Avalon to join the Acolytes.
