Luke (Japanese: ルーク Romaji: rūku) is a traveling treasure hunter in the Slayers series. He is around 21 or 22 years old. He worked as an assassin until he met Milina, who convinced him to reform. The two have been traveling together working as treasure hunters ever since.
Luke has a piece of Ruby Eye Shabranigdu in his soul. In the fourteenth novel, Milina dies and Luke is overcome with hatred, allowing the fragment to awaken. Lina confronts Luke-Shabranigdu in the final novel, where she breaks open the Demon Blood Talismans and releases the power within them to destroy him. Luke's strong desire for death allows Shabranigdu to be destroyed by his own power, something that would otherwise be impossible.
In The Cursed Sword of Bezeld, Luke makes his first appearance. He and Milina offer to protect Sherra from the men pursuing her, unaware that she is a mazoku. Luke later helps Lina defeat Galva after Dulgofa transforms him into a large demon. Dulgofa casts Raugnut Rushavna on the demon to make it immortal, allowing it to regenerate faster than Lina's Ragna Blade alone can harm it, but with the help of Luke's Ruby Eye Blade they manage to overwhelm it.
In the tenth novel, Luke and Milina are serving as bodyguards to Laavas Langmeyer. He initially comes into conflict to Lina, until she reveals that Laavas has been deceiving him.
In Hatred in Sellentia, Luke and Milina are hired as bodyguards for High Priest Kereth Rolencio of Sellentia. During a fight, Milina is struck by a poisoned dagger thrown by assassins hired by High Priest Francis Demitory. Luke takes Milina to a shrine run by High Priest Sainfort, but he refuses to help her because she was working for his rival Rolencio. Luke next takes her to Rolencio, but no one at his shrine knows Resurrection, and Milina dies. Filled with hatred, Luke vows to kill all of the High Priests in Sellentia, who he regards as responsible for her death. Luke succeeds in killing Demitory and Sainfort, but is overcome with grief and runs away without killing Rolencio.
In Demon Slayers!, Luke's intense grief and hatred over Milina's death causes the awakening of the piece of Shabranigdu within him. Luke-Shabranigdu challenges Lina and Gourry to a final battle. He tells them that he doesn't know what to do. He hates humans because a human killed Milina, but he also hates mazoku because Dynast engineered the situation in Sellentia. He hates the world for taking Milina away from him, but he still loves her. So, Luke-Shabranigdu will offer Lina an opportunity to destroy him. If Luke-Shabranigdu prevails, he will destroy the world; if Lina prevails, he will leave it in peace. He grants Lina and Gourry unlimited magical energy, allowing Lina to wield Ragna Blade continuously and Gourry to utilize the full potential of the Blast sword, so that they will have a chance against him. Even with these advantages, the two are losing until Lina breaks open her Demon Blood Talismans. The energy of the three other ma-ō within them severely wounds Luke-Shabranigdu, but does not destroy him. He says that there is nothing left for Lina to do, because Shabranigdu cannot be harmed by his own power. Lina breaks open the fourth talisman anyway, and Luke's strong desire for death allows Luke-Shabranigdu to be destroyed by his own power.
Luke was very competitive towards Lina, who he viewed as a rival.
Luke was in love with Milina, who never openly returned his affections.