Part of the mutant rebellion that led to Magneto gaining power, Lionel and his brother Madison were deemed damaging to the image Magneto wanted to create. To this end, they were sent to Santo Rico, a small Central American country to take it over and generally be forgotten.
Arriving there, the Jeffries brothers made quick work of warlord El Toro and his army, eventually capturing El Toro and claiming control of the country. As a warning to any humans who might try and resist, Lionel mutated El Toro into a distorted man-bull creature and imprisoned him in front of El Toro's former mansion, and their new base of power.
Years later, the Hood, a human criminal wanting to create a power-base led his criminal army into Santo Rico to depose the Jeffries brothers. Making short work of the mutant army the Jeffries used as a police force, the Hood and his army eventually encountered the Jeffries brothers themselves. Using their powers to reshape flesh and metal, the two initially began tearing the army apart, with Lionel absorbing Piledriver and Bulldozer into his monstrous flesh-form before the Hood allowed himself to be absorbed by Lionel, a move that resulted in the Hood's demonic powers overwhelming Lionel and destroying the flesh-form he had created for himself. Wanting to surrender, the Hood instead shot Lionel in the head, killing him.