Personality: Tabitha has always been somewhat of a loose-cannon. Her headstrong attitude, and take-charge personality make her a lot of fun to be around, but on an interesting sidenote, her powers seem to be the perfect match for her almost overwhelming attitude.

Strength: Meltdown possesses the normal strength of a girl of her age, height, and build who engages in moderate regular exercise.

Known superhuman powers: Meltdown can create balls of energy of an unknown kind, which she calls her "time bombs." These "bombs" explode with concussive force. She can produce marble-sized "bombs" which have little concussive impact and which she uses for playing pranks. She has produced "time bombs" ranging up to the size of beach balls, which, when they explode, can smash tree trunks and even metal objects. To at least some extent Meltdown can control the amount of time between the creation of one of her "bombs" and the time it detonates. She can also mentally muffle the sound of the detonation to a limited extent. The limits on her power to create and control her "time bombs" are as yet unknown.

Near Washington, D.C. the train was wrecked on a whim by the cosmic entity calling itself the Beyonder. Thinking he was a mutant, Boom Boom accompanied him. The Beyonder abandoned her but returned and took her to Xavier's school. There the X-Men attacked the Beyonder, who escaped. Boom Boom, frightened and bewildered by witnessing the attack, left, but was later found by the Beyonder, who brought her to a distant planet that he called "World Complex Headquarters" of the alien Celestials. There, threatening to destroy the universe, the Beyonder fought and seemingly defeated a number of Celestials. (However, that planet was not truly the Celestials' headquarters, and the Celestials allowed the Beyonder to "defeat" them, presumably in order to observe him in action.) Terrified, Boom Boom demanded that the Beyonder transport her back to Earth and leave her, and the Beyonder complied. Back on Earth, Boom Boom alerted the Avengers about the Beyonder. Summoning the Beyonder, Boom Boom thereby led him into an ambush by the Avengers and other costumed champions. The Beyonder, who had regarded Boom Boom as his only friend, allowed the Avengers to defeat him, but then left. Boom Boom left during the battle.

She eventually encountered the mutant criminal known as the Vanisher, who made her a member of his gang of thieves, the Fallen Angels, and taught her how to steal. Believing that the Vanisher was treating her badly, Boom Boom alerted X-Factor, whom she believed to be a group of mutant hunters, about him. But when two members of X-Factor arrived, who were actually the Beast and Iceman, Boom Boom changed her mind about turning in the Vanisher and used her "time bomb" power on the Iceman as a prank. The Beast and Iceman pursued her and caught up to her in their costumed identities. She agreed to leave the Vanisher's gang and live at X-Factor headquarters instead.

Later, after Boom Boom set off another of her "time bombs" in the X-Factor laboratory as a prank, the Iceman pursued her through the headquarters. Another member of the Vanisher's gang, Ariel, used her powers to enable Boom Boom to escape X-Factor headquarters. Thereafter, Boom Boom stayed for a time with the Fallen Angels. After an adventure on another planet with the Fallen Angels, Boom Boom returned to X-Factor headquarters only to be captured by the anti-mutant organization called the Right. When Boom Boom regained her freedom, she went back to X-Factor and joined the Xavier Institute.

When she got there she developed a crush on Samuel Guthrie, and recently went though a deeper and more drastic change in looks and personality and changed her code name to "Meltdown."