In the series
In Storm Front, after he lost his job at the SilverCo, Victor Sells discovered his latent magical talent, and he became obsessed with power. He started spending all his time practicing in his attic. Sells started the manufacture of a drug known as ThreeEye in order to make money, a drug that opens the third sight for normal mortals and hooks harder than cocaine. ThreeEye was cutting in on Marcone's drug business.
Sells discovered that he was more powerful when he used rage and lust to power his spells. He got backing from Greg Beckitt and Helen Beckitt promising to help them take revenge on John Marcone. He also tapped the lust from Tommy Tomm, Jennifer Stanton, Linda Randall and turned Gimpy Lawrence, one of Marcone's men.
Harry Dresden eventually confronts Sells at his lake house, where Dresden interrupts Sells's spell, then deflects a wave of flame aimed at him, which causes the house to catch on fire. Dresden is then shot in the hip by one of the Beckitts and Sells creates scorpion constructs which he sends at Dresden. Dresden successfully sweeps them off the balcony, but Sells then summons the toad demon, Kalshazzak. Dresden frees Kalshazzak from Sells's control, then tackles Sells as he attempts to escape. They fight and fall over the balcony, both grabbing at the railing. The toad demon bites Sells, and both he and the toad fall to the first floor where they are both destroyed by Sells's scorpions as the house burns down. Sells perishes and is also implicated as the head of the ThreeEye drug ring.
}} In Changes, Donar Vadderung states that the curse he used was a less advanced Bloodline curse—but that since he is stronger than a normal acolyte, it's possible he was being backed by the Black Council.
In Cold Days, the Summer Lady, Lily, implied that the Contagion—later named Nemesis—corrupted Victor Sells the Shadowman, "destroyed a father's love for his facility by twisting it into maniacal ambition". Lily also implied that two other of Dresden's first three big case: Phillip Denton and his Hexenwolves, and Leonid Kravos The Nightmare were also infected.
Word of Jim
In discussing how he plotted out the series, the author described Victor Sells as, "the kind of dark version of what he [Dresden] can do"