|“||I summon you, Elyaas who swims in the midnight seas of eternally drowning souls, Elyaas who lurks in the shadows that surround Pandemonium, Elyaas who bathes in tears and plays with the bones of lost sailors.||”|
In 1878, Elyaas was among the many blue demons summoned by Magnus in aiding Will Herondale look for the demon that cursed him. Magnus immediately realized that he made a mistake summoning him as he was not precisely as blue in person as he was in illustrations and sent him back.
Elyaas was once again summoned by Magnus in 2007 as a job for Caroline Connor of Pandemonium Enterprises. While waiting for Connors' return, Elyaas, after being summoned early in the day, was kept in his pentagram in Magnus' apartment, where it dripped slime and became more viscous as the day drew on. He soon recognized Magnus from the last time he'd summoned him and expressed interest in the result of Will's quest for that blue demon, though referring to him as Bill Herondale. Elyaas also listened in on Magnus' conversations and insisted on recommending gifts, such as a mixed tape and scented candles, for Magnus' boyfriend, Alec, making the warlock decide that he was even a worse roommate than Raphael Santiago.
When Connors finally returned and revealed that her employers intended to let the demon curse the mermaids of New York, Magnus annoyingly expressed disdain in his unnecessary summoning, offering to do something about the mermaids himself instead, despite the demon's eagerness. Disappointed, Elyaas, as Magnus sent him back, furiously told Magnus that Alec, being a Nephilim, would never never truly love him, and that Magnus's father would eventually bring him to the Void with him and the other demons. His last word, however, was his continued suggestion that Magnus buy Alec scented candles.
In 2012, Elyaas was among the demons summoned by Magnus for one of the temptation lessons for his warlock son, Max. He tried to tempt the child to join him, telling Max of his naturally inclination to evil due to his dark lineage. His effort was unsuccessful as Max had been well-taught by his family, including his Uncle Jace, which Elyaas responded with an answer that hinted that the demon had met Jace at some point. Elyaas commended Alec and Magnus for making their relationship work, but when Alec noticed him reaching for Max, which the demon claimed was just an instinctive act, Magnus banished him.
Elyaas, like typical cecaelia demons, is an ugly and slimy being. Elyaas is mostly shapeless, like a blob, with a head like a human's, except with eyes set close together, his nose and mouth combined in a triangular slit. He has no arms, a short torso, and short and thick tentacles. He is covered in greenish-black slime and has a mouthful of slime, making him sound like a middle-aged man speaking underwater.
- Clockwork Prince (first mention)
- What to Buy the Shadowhunter Who Has Everything (first appearance)
- The Land I Lost
- The Lost Book of the White (set to appear)