The Groosalugg is a native of Pylea, a hell dimension where humans are treated as slaves and called cows. He is part demon and part human, but apparently more human since his only non-human physical characteristic is a pair of brightly colored eyes. He also speaks with unique syntax, bordering on kitsch. Because of his human heritage, he was banished to the "Scum Pits of Ur" where he was to die, but instead defeated every creature that attacked him. This earned him a reputation for bravery and combat skill, and as such he wandered the countryside as an undefeated champion, or Groosalugg. In Pylea there is a prophecy that the Groosalugg will one day com-shuck, or mate, with the entity that has "the curse," which in this case comes to mean Cordelia's visions. After the two have mated, Cordelia's visions will be passed on to him. Since Pylea is dominated by monks loyal to Wolfram & Hart, this would put the instrument of The Powers That Be under the control of evil. Cordelia does not want this, at first because she believes the Groosalugg to be more demon-like, but this objection falls when Cordelia meets him and sees that he is, in fact, very handsome and nearly human. However, Cordelia still does not want to consummate their relationship because she does not want to lose the visions. Groo ends up proving that he is a good man, not a tool of evil, and helps Cordelia and the rest of the characters to escape Pylea. At the end of season 2, Groo is installed as monarch of Pylea, the first to preside over the freedom of the human former slaves.
Midway through season 3, Angel and Cordelia are close to starting a relationship when Groo unexpectedly appears in Los Angeles. He explains that he had been deposed in a revolution on Pylea, and decided to find Cordelia again. The feelings that Cordelia have for Angel are immediately put on hold, and instead she chooses to rekindle her romance with Groo. She even goes as far as to find a mystical spell which allows her both to have sex with Groo and to retain her visions. Angel is jealous of Groo for many reasons, including that Cordelia has chosen Groo over him and that Groo is just as formidable a fighter as himself. For a time, Angel is concerned that Groo will replace him, but Wesley assures Angel that he remains their reason and drive for fighting the good fight in the first place. Despite this, unable to withstand being witness to the relationship between Cordelia and Groo, Angel gives them money and asks that they go on an extended holiday.
When Cordelia and Groo return, they find that some terrible things have happened in their absence, such as Connor being stolen by Holtz and Wesley having betrayed the team in an attempt to protect Connor from a prophecy that seemed to foretell Angel killing Connor. Cordelia immediately begins to pay more attention to Angel, and Groo starts to realize that Cordelia does not love him but rather Angel. In the last episode of season 3, Groo finally musters up the courage to tell Cordelia this, and he then leaves Los Angeles for parts unknown.
In "After The Fall", the Groosalugg is present in Los Angeles, now residing in Silver Lake and serving as champion to