At Gaius Point (Warhammer 40,000)

Emerging from the wreckage of a crashed Thunderhawk gunship, Brother Zavien of the Flesh Tearers embarks on a desperate hunt. His quarry is more dangerous, more vicious and more deadly than any other in the jungles of Armageddon. Zavien knows this, because he hunts Jarl, his own battle brother, taken by the Black Rage and a threat to friend and foe alike. Read it because
With their vicious tempers and unfettered fury, Flesh Tearers are often their own worst enemy, but it's rarely been as literal as it is here, in Aaron Dembski-Bowden's take on the boys in black-and-crimson.