Fager wrote Spindelkonungens pyramid [sv], the first role-playing game adventure published in Swedish.

[4][5] After among other things an army career, Fager made his debut as a writer in 2009 with the short story collection Swedish Cults (Svenska kulter) that received a most favourable review in Swedish newspaper Dagens Nyheter[6] and launched Fager's career as full-time writer.

Set in present-day Sweden, his interconnected stories form a modern part of the Cthulhu mythos with entities such as Dagon, Hastur and Nyarlathotep making appearances.

[7] In the 2010s he has written role-playing supplements for such games as Kult, Twilight: 2000, Call of Cthulhu, Tales from the Loop and the new release of Chock, originally a Swedish translation of the RPG Chill.

[8] In 2022 Fager and artist Peter Bergting's graphic novel The Crows was published by Dark Horse Comics.