|Age||19 (at time of death)
Caelan was an exiled vampire who first appeared in Dark Days. He had 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 became a vampire, but could not get out of his cage. At dawn, he returned back to his normal state and the lock opened. In Death Bringer, Caelan became Valkyrie's secret boyfriend, but was drowned by her at the end of the book.
He was in love with a girl called Anna but their relationship was not approved by their parents so they decided that they were going to run away together. Her family owned a tavern where she worked and one day a man Visited. He kept coming back and got into a fight with two other men in the tavern, one who was protecting Anna, as he was in love with her. He then threw them across a room when he was confronted. He and Anna eventually started talking, and she told him about herself, Caelan and their plans. One night when Caelan was standing beneath her window, the vampire bit Caelan and he fell into the tavern cellar. When he woke, 3 days later, he found her family dead. All he cared about was the blood, and he drank it off of the walls and the floor. During those 3 days, the vampire had told Anna that Caelan had left without her and had even orchestrated it so that she would return to the house to find Caelan with the bodies of her dead family. She ran to the vampire and he slept with her and when he was finished he cut out her heart and left it for Caelan.
Friday Night Fights
When Valkyrie is kidnapped, she is thrown into a cell which she later realizes she shares with Caelan. They start talking and he tells her about his past and she explains how she is looking for Skulduggery. Caelan then says that he knows how to get in touch with Chabon, who currently had the Murder Skull, and so they made the agreement that if she got him out then he would help her in return. Caelan is then taken away to fight in the pit against another vampire called Victor while he is only half vampire. Valkyrie is thrown in the pit and catapults them up into the crowd, using her elemental powers. She then runs away and she finds Caelan again. He injects himself with more serum, so he is 100% human, and helps her escape. Valkyrie then tells him that he saved her life so he didn't owe her anything but he says that he will. He then walks away and is not seen again until Dark Days.
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". In The Maleficent Seven this Vampire was revealed to be Hrishi, Dusk's only 'friend'
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.
In Mortal Coil, Valkyrie convinces Caelan to taste her blood to see if he can recognize what is so special about her blood. He reveals that he has strong feelings for her admitting that he believes that they are two people who would mean either everything to each other or nothing at all. Valkyrie is flattered and shows clear attraction to him but tells him she can't be with him due to being with Fletcher.
Caelan agrees to taste her blood but refuses to bite her neck in case he cannot control his monstrous side, and instead offers Valkyrie a penknife which she used to cut herself so that he may sample her blood. He immediately looses control and drives Valkyrie back and almost bites her, but instead turns it to a kiss. Valkyrie kisses him back but then trips him and pulls away. Caelan attempts to kiss her again, but Valkyrie insists it won't happen again. Caelan then tells Valkyrie that he has changed his mind about putting distance between them and tells her he loves her, but Valkyrie turns him down due to her relationship with Fletcher and due to Caelans coming on too strong.
He is later seen stalking Valkyrie appointing himself as her secret guardian until he can no longer control his transformation and is forced to seek refuge in the Midnight Hotel.
At the Hibernian, he rescues Valkyrie from a possessed Fletcher. After the events, he lets Scapegrace and Thrasher out of their cells and tells Valkyrie he has found the formula that Dusk uses to stop himself from turning into a vampire by night and has learnt how to make more of it. He continues by saying that he can become human for her and tells her again that he loves her. Valkyerie insists that there will be nothing between them, but Caelan reveals that he can hear how fast her heart beats every time she looks at him. Valkyrie still rejects him, but Caelan says he will prove himself. As Caelan leaves Valkyrie thinks he will kiss her, but they don't, leaving Valkyrie disappointed.
In Death Bringer, it is revealed that Valkyrie cheated on Fletcher with Caelan as she feels Fletcher is too "boyfriendy." She finds the fact Caelan is dangerous attracts her. However, he becomes very obsessed with her and she does not like it so she calls the relationship off.
Caelan does not take it well and prepares to turn Valkyrie into a vampire by biting her. Valkyrie then calls Fletcher who insults and then fights a fully fledged vampire Caelan, smacking a baseball bat against his head and embedding an axe in Caelan's shoulder blade. Caelan wounds Fletcher and Valkyrie grabs Caelan and throws herself and Caelan off the edge of the pier into the sea. Sea water is lethal for vampires, closing up Caelan's throat and suffocating him to death.
The Maleficent Seven
In a conversation between a vampire named Irina and Dusk, the vampire whom Caelan killed is revealed to have been Hrishi, Dusk's "only friend". Caelan is also revealed to have repeatedly become obsessed with various women and had apparently stalked, tortured and eventually killed them.
Caelan is strongly pictured as a self-loathing person during his appearances in the series. Although in human form he is seems generally kind and harmless, he 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 Caelan's 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".
Caelan appears to be maybe nineteen or twenty, but is probably over a hundred years old, tall, with black hair that shines, dark eyes and narrow cheek bones. Valkyrie also describes Caelan as "good looking". This is probably why Fletcher feels so threatened by him.
Caelan possesses all the usual skills a vampire has, (increased speed, strength, agility, vision, perception) and also sheds his skin at dusk, taking on the vampires' true form. Caelan seems to be inferior to Dusk, who easily beats him in their fight. This is because Dusk is many (maybe hundreds) years older than Caelan, and thus, Dusk has a lot more experience, especially when it comes to blood, of which Dusk is a "connoisseur".
- It is unknown if Caelan is his real name or a name he gave himself.