Context: Theo Bell is a vampire, he was born in 1829, to an enslaved family. His last memory of his father is being pried from his leg to be sold to Bell plantation at the age of 5, along with his mother and sisters.
Eventually, he escaped, and strangled a bloodhound with one hand along the way. He then joined the Underground Railroad. One night, a mission went bad, and Theo, about to be trapped by his pursuers, was drunk dry by a vampire who had admired his exploits for years.
Understanding his new power as a vampire, Theo escaped his pursuers and returned to the Bell Plantation he escaped from. There, he took up a whip, and slew his enslaver, "Master Bell", and flew into a vampiric Frenzy. When he came to, he was in the plantation's Slave Quarters, surrounded by bodies.
After slaughtering every living being on the plantation, slaver or slave, Theo took the name Bell to remind himself that HE has the power now.
Bell would go on to be the most feared enforcer of the Camarilla (vampire mafia) for many years, before snapping and gutting the leadership. He then left the organization, taking much of Clan Brujah with him.
Unrelated to VtM lore: Vampires drinking the KKK dry is a great fucking story