Caelan

Caelan is an exiled vampire who first appears in Dark Days. He has some sort of grudge against Dusk; however this has not been explored in the books. He used to live in a cage with a time-lock. At sundown he becomes a vampire, but can't get out of his cage. At dawn, he returns back to his normal state and the lock opens. In Death Bringer, Caelan becomes Valkyrie's secret boyfriend, but is drowned by her at the end of the book.

Caelan helps out Valkyrie Cain by organising a meeting with the notorious wheeler, Thames Chabon. He has been exiled from the vampire community because he killed another vampire. When questioned by Skulduggery about why, he merely said "He had it coming".

After trying to help Skulduggery and Valkyrie find the Revengers' Club by talking to Moloch, he was banished and his home was destroyed. Valkyrie offered for him to stay at the Midnight Hotel, and he agreed.

At Croke Park Stadium, after Valkyrie is bitten by Dusk, Caelan saves her but loses to him.

Caelan is pictured as a self-loathing person during his appearances in the series. Although in human form he is seems generally kind and harmless, he becomes quickly becomes obsessive, intense and angry when his feral side is tempted. He blames himself for everything, particularly bad things that happen to Valkyrie. He is shown to be unable to control his obsessive personality when he falls in love with people and reveals during Death Bringer that his former loves have died due to being unable to keep the monster inside him. At one point he reveals that he killed one of Dusk's friends who tried to convince him to stay away from mortals and hide in the darkness, worried that Caelans behaviour risked the safety of the vampires. This causes him to be exiled and hated amongst other vampires. When he is around Valkyrie he shows undying affection towards her, although he cannot justify why he loves her when he is questioned, and when Valkyrie breaks up with him he immediately becomes abusive and tries to infect Valkyrie for the sake of their "love".