Title: The Demon Lord's Hero
Link: https://www.webnovel.com/book/the-demon-lord's-hero_18131619205386105
Genres: Fantasy
Tags: Adventure, R-18, Gay, Violence, summoned hero, World Domination, polyamory, boy love, evil-protagonist, mature-content
Synopsis:
Gavin was your average high school nerd; loner, preferred books over people. One day, out of the blue, he was summoned to a world filled with magic and creatures straight out of a fantasy novel.
He was told that the Demon Lord was about to attack the kingdom and he was the only once who could stop it all. He was also told that he wouldn't be able to return home until he killed the Demon Lord.
Little does he know, the Demon Lord knows all about him and has plans for him. The Demon Lord want to make the Hero his and for the two of them to take over the world together.