The Night Lords trilogy follows a shrinking squad that has Uzas, a guy succumbing to Khorne's influence, and Cyrion who was blessed/cursed by Slaanesh and was also slowly succumbing to the desires it unlocked. Neither was loved or loved their God, but that dependency was there. More like a drug addict, especially in Cyrion's case.
To continue on the ADB fluff, because IMO the guy really does do the best he can at getting the "feel" of 40K right, the warband led by Iskandar at the start of The Talon of Horus is a barely held-together mess. They're constantly fleeing from persecution, they're unable to repair their vessel fully and even coming to neutral stations for repair and refitting is dangerous. They have Khornate soldiers, a Slaneeshi Emperor's Children character, and a Thousand Sons leader in Iskandar and his Rhubricae.
They're always scraping by, with never enough forces to truly crush an enemy. They spend their time running scared from Emperor's Children fleets as well as other Legions due to their loose allegiance with some of the Sons of Horus remnants. Everyone's killing and scavenging other Legion's gene-seed, weapons and vessels because there's no means to make more, not without hefty cost from the Dark Mechanicus.