Felix Jaeger is the disowned son of an Empire merchant, a poet, and the rememberer and travelling companion of the famous Dwarf Slayer Gotrek Gurnisson. Felix once drunkenly pledged to travel with Gotrek and record his death. In WAR, both of these characters can be found in The Screaming Cat, a Tavern in Altdorf. The adventures of Gotrek and Felix can be read in the "Slayer" series of novels, written by William King and (from "Orcslayer" and onwards) Nathan Long, and published by The Black Library, the publishing arm of Games Workshop.
The youngest son of a wealthy merchant family, Felix attended a prestigious university and had a promising career as a poet before being expelled by the university and disinherited by his family for accidentally killing a fellow student in a duel. Felix fled after the incident and fell in with the wrong crowd, eventually becoming an instigator of the infamous "Window Tax Riots" of Altdorf, initially meant to be a peaceful protest against an unfair tax, but the demonstration quickly turned into a riot. The Reiksguard, whom the Emperor had ordered to pacify the mob, charged headlong into the citizens of Altdorf, with disastrous results. Horrified Felix attempted to stop the attack by putting himself between the charging knights and a crowd of panicking women and children. Whether moved by Felix's courage or stupidity, the Dwarf Slayer, Gotrek Gurnisson, intervened, cutting down a score of knights before pulling Felix to safety. After the pair went on a celebratory drinking binge (at a nearby tavern) of truly epic proportions, Felix woke up to realise (much to his chagrin) he had pledged to follow Gotrek across the world and record his doom in an epic poem.
Felix has long given up any hope of ever returning to his family alive. However, the chapters of each book are prefaced with an excerpt from "My Travels With Gotrek", a book supposedly authored by Felix and recounting the pair's adventures together and recording Gotrek's eventual doom. This implies that Felix manages to somehow survive Gotrek's eventual fate, altough he once suggests publishing the initial phases of the work prior to it's completion. Despite his initial reluctance to comply with his misbegotten oath, Felix has warmed up (or possibly resigned himself) to his oath and has even been romantically involved with many women in his travels, the most notable of which is Ulrika Straghov, a proud swordswoman and the daughter of a Kislevite baron. Unfortunately she was made a Vampire in the novel "Vampireslayer" and their relationship was forced to end.
Felix wields "Karaghul", a blade with a dragon hilt recovered from the fallen hold of Karak Eight Peaks in the novel "Trollslayer". A relic of the "Order of the Fiery Heart Templars", it was forged to slay dragons. Although Felix is a talented swordsman and duellist, in most situations Gotrek saves Felix from certain death as the odds are often too great for even such a skilled swordsman as Felix to endure. Karaghul has taken over Felix's rational thoughts on a few occasions, such as when dragons of any breed are nearby. The sword then enrages Felix, drawing him to confront the beasts head on, not unlike Gotrek whose quest for his own doom draws him to confront the strongest foes in hopes of being killed in combat. In a chance encounter with old "friend", and a rival in love for Ulrica, magician Max Schriber, the magician tells him that Gotrek's axe is seemingly keeping them both young and strong, for some purpose hidden to even the Slayer himself.
Felix has appeared as one of the two lead characters in all eight of the Slayer series' novels. Felix also appeared in the 1992 edition of Games Workshop's "Warhammer armies: The Empire", in a short story featuring Gotrek and another of his companions from the Black Library series, Snorri Nosebiter.