Tom and his cousin, Sean Cassidy, were rivals for the affections of a woman named Maeve Rourke. Maeve married Sean; however, her death seemed to revive their dislike for one another, not to mention Tom secretly raising Sean's daughter, Theresa.
When Tom became a criminal, he came into conflict with the law and was apprehended. While serving time in prison, Tom met and befriended Juggernaut.
The X-Men initially clashed with Tom and Juggernaut at Cassidy Keep. He and Juggernaut were involved in many schemes. On one occasion Juggernaut sought to share his power with Tom, in essence creating two Juggernaut-like beings.
After being shot by Cable, Tom was taken to France, where doctors grafted a wood-like substance onto his wounds, healing him and allowing him to channel his bio-blasts directly through his fists. Unfortunately, due to a genetic virus, the substance spread over Tom's body. He sought to use Deadpool's healing factor as a cure.
He later attacked Sean and Generation X in a partially transformed state. During the attack on the school, he took control of Emma Frost's body to hit Sean, hoping to force him to kill her. Knowing that Black Tom wouldn't stop until one of them was dead and that Sean couldn't bring himself to kill her, Emma took control of Sean's mind and sent a powerful sonic scream in her direction, apparently ending her life. After this, Penance intervened and defeated Tom.
When he encountered the X-Men again as part of the Brotherhood, Tom, like the rest of the Brotherhood, was sucked into Shen Xorn's head and transported to the Mojoverse. There, they sold Juggernaut and Nocturne to Mojo and, in return, they were sent back to Earth.
Tom has since shown great remorse for the death of Squid-Boy and claimed that his secondary mutation had affected his mind. Juggernaut visited him in prison, forgiving him for the death of Sammy. Tom correctly assumed that Juggernaut had not come to forgive him, but had returned because he was hearing voices again, and wanted to know if there was any way he could find redemption. Tom told him that he did not believe redemption was possible for either of them.
He was seemingly repowered, using his powers during an encounter with Deadpool.
House of X
Tom was eventually welcomed to the new mutant island of Krakoa, created by Xavier, Magneto, and Moira X. He entered through the teleportation gateway alongside other villainous and fractious mutants, who had been invited to join the nation in order to heal mutantdom and start over as a whole species together. Discovering that he could share a synergistic link with the landmass of Krakoa in order to vastly enhance his powers, he became Krakoa's chief of security and a member of X-Force.
Powers and Abilities
Bio-Organic Thermokinetic Blasts: ability to generate blasts of concussive force or heat by using wood as the focus for his power; typically a wooden shillelagh. Following genetic engineering, Cassidy can channel the energy he generates directly through the parts of his body that were grafted to a wood-like substance.
Since his transformation into a plant-like being:
Plant Growth (formerly): Cassidy could grow to immense size.
- Superhuman Strength
- Healing Factor: could regenerate damaged or destroyed body parts with great speed.
Chlorokinesis (formerly): He could also mentally control all plant life within his vicinity.
- Plant Consciousness: could distribute his consciousness amongst plants he controlled.
- Life-Force Absorption: Cassidy could drain the life force of organic beings.
Genetic protection: Black Tom is highly resistant, if not immune,to Banshee and Siryn's sonics, and they are similarly protected from his bio-blasts.
His 'shillelagh' is a wooden club.