Most of Abyss' life is shrouded in mystery. It is known that he is the son of Mystique but neither he nor Nightcrawler realize they are brothers. It is also rumored that he fought his way out of Sinister&s labs. But instead of escaping, he fought his way into Apocalypse's lair and assassinated a Horseman by the name of Bastion. Impressed by the boy's tenacity, Apocalypse made him his youngest Horseman.
During the evacuation of Maine, Abyss was in charge of stopping the X-Men and the Sentinels from helping the humans escape North America. He kidnapped a young boy and used him to draw Quicksilver into the open. Obviously obsessed with impressing Apocalypse by capturing the son of Magneto, Abyss abandoned his main goal of stopping the evacuation and allowed it to occur. He met Quicksilver but was unable to defeat the X-Men leader. Quicksilver was able to save the kidnapped boy and defeat Abyss with the help of his fellow X-Man, Storm.
Following this defeat, Abyss was placed in charge of interrogating the mysterious man known as Bishop. With the assistance of the Shadow King and the Madri Abyss began his interrogation. The X-Men staged a daring raid to free him and Abyss allowed his ego to get in the way of completing his mission. This time it cost him more than just his objective, however. Abyss underestimated the strength of the mutant Banshee and his sonic scream. Flying into Abyss, Banshee cut loose with the full fury of his powers and it appeared that he ripped Abyss apart. Abyss has not been heard from since and it is assumed that he is dead. But whether a mutant with his powers and no true physical form could ever truly die is unknown.