Billy (Bill-E) Spleen

Billy Spleen, nicknamed Bill-E by himself, is a character from Darren Shan's The Demonata series. He is half-brother of the main protagonist, Grubbs Grady, but he believed that Dervish was his father (and therefore, Grubbs his cousin) until Lord Loss revealed the truth in book 6, Demon Apocalypse. He suffered from the same disease (Lycanthropy) that led to the death of Gret Grady at the hands of demons. Dervish and Grubbs saved his life but he was not informed of that fact until a few months later. He also has a noticeably lazy eye. He is featured in Lord Loss, Slawter, Blood Beast, and Demon Apocalypse, and he plays a major role in the series. Although he and Grubbs were close at the start of the series, in Slawter and Blood Beast, their relationship is constantly tested by Grubbs's new friends.

In Blood Beast, Grubbs' friend Loch Gossel bullies Bill-E a lot, and this drives Bill-E to let Loch fall and die. This begins the reopening of the tunnel seen in Bec.

Bill-E's life ends when Grubbs kills him in Demon Apocalypse to avoid the reopening of the tunnel.

Grubbs Grady
Grubbs Grady, (short for Grubitsch Grady) is Billy's half-brother. Billy befriends him when he moves in with Dervish at Carcery Vale. Like his Uncle Dervish he also has a cruel taste in pranks. Yet Grubbs never exactly told Bill-E that he was his half-brother as he intended to in the end of Slawter, he still waits for the right moment to bring it up.

Cal Grady
Cal Grady was Grubbs (and Billy's) father and Dervish's brother. It appeared that he was happily married to Sharon, his wife, but it turned out that while visiting Dervish in Carcery Vale he had a one night stand with a local woman, resulting in the birth of Bill-E.

Ma and Pa Spleen
Ma and Pa Spleen are Bill-E's over protective grandparents. In Blood Beast, they are killed by Grubbs when he is struck with lycanthropy, but later revealed to be killed by Juni Swan (or Nadia Moore).

Dervish Grady
Dervish Grady is Billy's uncle. In Lord Loss, Bill-E believed that Dervish was his own father. This was untrue as Bill-E's father was Cal Grady, Grubb's father. He battles Lord Loss along side Grubbs when fighting to cure Billy of his Lycanthropy.

Loch Gossel
Loch was Grubbs' best friend after Grubbs got settled into school via Bill-E. Bill-E and Loch dislike each other due to their contrasting personalities; Bill-E is shy and studious while Loch is a crude jock. Because of this, Loch teased Billy and became a bully. Bill-E often protests on why Grubbs would hang out with such a person and that he should stand up for his cousin/brother whenever Loch was around.

When Grubbs, Bill-E, and Loch go searching for Lord Sheftree's treasure, Bill-E and Loch did not work together as amiably Grubbs thought they would. Both of them act cruelly which almost causes them to kill each other. Their hatred finally got the better of them when Loch was clinging for his life after losing his footing when excavating the tunnel the trio had found. Bill-E was about to snatch Loch's hand when instead Bill-E swept it away (mimicking a prank Loch always played on Bill-E). After Loch's death, Bill-E began to feel remorse for Loch claiming that he never wanted any harm done and that the whole gimmick of Loch's prank was unintentional.

Lord Loss
Billy first meets Grubbs, who is actually his half-brother, in Lord Loss. They soon become good friends and spend a lot of time with each other. At the end of Lord Loss, Dervish tells Grubbs that Billy is really his brother, but they decide not to tell Billy.

Slawter
In Slawter Grubbs and Dervish take him to the "Slawter" set with them.

Blood Beast
In Blood Beast, his relationship with Grubbs becomes strained. Grubbs now has a group of new friends, including Loch Gossel, who constantly picks on Billy, and he harly spends any time with Billy anymore. The day after Grubbs's party, he becomes very frustrated with Loch and decides to go look for Lord Sheftree's treasure. After Grubbs explains to Loch what the treasure is and how he and Billy used to go searching for it, Loch decides to join Billy in the search; because he is not feeling well, Grubbs does not want to go, but the other two convince him to join them. After a long time of searching, Loch is about to leave, but Grubbs recognizes the place where they are from when Billy and he were spying on Dervish in Lord Loss, so he decides to dig one last hole there. What they do not realize at the time is that this is actually the entrance to the cave from Bec after having been filled in. They begin to think that this must be where the treasure is buried, so the decide to dig here everyday until they find it. One day, after the hole has gotten to be several feet deep, Billy is digging by himself in the hole until he breaks through the dirt that had been used to fill in the hole, revealing the shaft that leads to the cave. After some hesitance from Grubbs, the three go down into the cave. The all begin to explore the cave for the treasure. After giving up on the treasure, Billy and Loch decide to try to climb one of the cave walls, but Grubbs decides not to because he is feeling ill. As they are climbing, Loch slips and falls off of the wall, hitting his head. As Billy goes to get help, Loch dies from head trauma. Billy blames himself for not catching him as he fell, and he becomes very depressed; Grubbs tries to comfort him be telling him that he would have just been dragged down with Loch because of his weight, but it does not help much.

Demon Apocalypse
Bill-E appears alongside Dervish when Grubbs, Kernel, and Beranabus travel back through time to stop Lord Loss from opening the tunnel in Carcery Vale. After the magicians defeat Lord Loss and his familiars, it is revealed that the demon invasion is inevitable. Because Loch Gossel was killed in the tunnel, his blood was used to open a portal to the realm of the Demonata. The only way to interupt the invasion is to kill the one person that killed the sacrifice. Bill-E then exclaims that Loch died by his hands. When Loch was hanging for his life while exploring the tunnel with Grubbs and Bill-E, Bill-E was about to grab Loch's arm, but instead pulled it backwards (a insult that Loch did on Bill-E numerous times) causing Loch to fall to his doom. Everyone realizes that there is an ultamite to solving this: either kill Bill-E causing one death to save millions, or let Bill-E live causing vice-versa. Grubbs steps forward to murder his half-brother but does it discreetly; he pumps magic through Bill-E saying that if they join together and think of joyous memories, they would bring the destruction of the portal. Grubbs instead causes Bill-E's heart to stop, giving him a peaceful death. Afterwards, Bec soon places herself in Bill-E's dead body, giving her both a place to house her soul access to all of Bill-E's memories.

Death's Shadow
Though not appearing physically, some of Bill-E's faintest memories are told by Bec.

Wolf Island
He was mentioned by Grubbs when he saw Antione's labotory repulsed to think both Gret and Bill-E were almost about to sent in The Lamb to be experiment.

Dark Calling
He was mentally insane inside of Death along with Beranabus and the other dead souls.