Agent Valente was an FBI agent who was called to investigate the mysterious disturbances caused by Sam and Dean in Season Seven episode Slash Fiction. So far he has only appeared in this episode. He pretends to be a good-natured FBI agent but is in reality a monstrous Leviathan who appears to have no trouble containing his hunger. The Leviathan boss may have ordered him to possess an FBI agent as he may have needed someone inside the police force.
Season 7
Leviathan Agent Valente
Like all the other Leviathans, he was inside Castiel's body when his mere presence caused Castiel to slowly melt and disintegrate. Castiel walked into a reservoir and the Leviathan which possessed Valente swam out into the sewers and possibly possessed Agent Valente during one of his former missions.
Hunting the Winchesters
In Slash Fiction, the Leviathans construct replicas of Sam and Dean who are themselves Leviathans. The Leviathan Sam and Dean head to a diner and after debating the importance of the real Winchesters, they ask a kid to activate his camera and start recording. They proceed by shooting everyone in the diner in a bloody massacre, capturing the slaughter on film.
Agent Valente (far right) investigates the carnage the Leviathans left in the diner
They kill the boy with the camera and announce to the world on film that the Winchesters are still alive. Soon afterwards, the FBI arrive at the diner where the massacre occurred and FBI Agent Valente arrives and views the footage of the massacre. He seems horrified and disgusted by the brutality the Winchesters displayed, and he seems offended by the ruthlessness the brothers showed when they slaughtered the boy with the camera. He is later seen with his fellow FBI colleague, where he says that if they do not capture the Winchesters it would mean less paperwork. He then goes off to hunt for the Winchesters.
Reporting back to Dick
Later, the Leviathan Winchesters are decapitated and their corpses are left and brought to the coroner's office. The coroner, who is also the sheriff's daughter, examines the Leviathan corpses and finds a mysterious liquid that is not blood. She asks her father why he lied to the FBI.
Leviathan Agent Valente reporting to his boss, Dick Roman
Agent Valente returns and says that she is right, it isn't blood, and reveals himself as a Leviathan. He then eats the sheriff and his daughter. Afterwards he phones his boss and tells him that some of his brothers have been decapitated and that Sam and Dean are still on the loose. He suggests copying the Winchesters again, but the boss turns this plan down, saying that the Winchesters "coming back from the dead again" will not be very believable - even for the American media. The boss also threatens to have Valente "bibbed" if he fails again.