Having the physical attributes of a fish, 10 year old Sammy Paré was a perfect target for the local bullies. Intent on stopping the harassment, Sammy plotted to shoot his tormentors. A meeting with Professor X saved Sammy from a potentially deadly showdown, and he chose enrollment at the Xavier Institute over murder.
Enroute to the Institute, Xavier found himself unable to contact the X-Men. Professer X took a detour over Ireland to help an X-Men mission at Cassidy Keep. On investigating, he found them assisting the Juggernaut in battle against their old nemesis - and Juggernaut's former partner in crime - Black Tom Cassidy. Sammy dove into the ocean and saved Juggernaut's life, which also began a friendship between the two. Cain became a surrogate father to Sammy, who also became friends with Carter Ghazikhanian and Icarus from the New Mutants. When Sammy's mother found out about his relationship with Cain she called Alpha Flight to bring him back home. Later Juggernaut suspected that Sammy's father was beating him, most likely because Juggernaut had been beaten by his own father as a child. When he and Northstar arrived at Sammys home in Vancouver and saw the boy covered in bruises, this angered Cain and he beat the father to within an inch of his life, also causing major property damage.
Recently, the team of super-powered Canadian operatives known as Alpha Flight was charged with retrieving all the young mutants residing at the Xavier Institute, as the Attorney General's office, the Governor of Connecticut, and the Canadian government had deemed the Institute unsafe for children to inhabit. This led to a clash with the X-Men, which was quickly halted after Sammy agreed to accompany the Canadian heroes back to Canada.
There, Sammy's father continued to beat him until Juggernaut came to visit. Juggernaut attacked Sammy's father and was subsequently arrested by Alpha Flight. Nevertheless, Sammy's mother left her husband and Sammy returned to the Institute, where he became roommates with Jay Guthrie.
Later, the Juggernaut infiltrated the Brotherhood of Evil Mutants, working as a double agent for the X-Men. When Sammy stumbled upon the group meeting, he assumed that Juggernaut was betraying the X-Men and lashed out at him, causing the group's leader, Black Tom Cassidy, to kill the young mutant, pulping his bones. After Sammy denounced Juggernaut on his deathbed, Cain was haunted by this for a long time after.
Can breath and speak underwater, fish-like appearance.