Grenpoli dropout and heir to the Rex fortune
Abacus Rex is the son of Evania and Virus Rex, and the sole heir to the Rex fortune. He was enrolled by his parents in the Political School of the Nine Hells in the city of Grenpoli, but he cut a deal with the mail room imps to have his tuition fees redirected to himself upon receipt and dropped out.
Abacus met Sitani Wo, Naedas Lutand, Taga, Tim Ocher, and Loopwyn Nacklebell while he was exploring Mechanus. He accompanied them into Sigil and allowed them to stay in his apartment on Turtle Lane until it was burned to the ground by werewolves.
He is currently staying at the Warm Coin Inn.