Warhammer 40k - Flesh Tearers Short Story - At Gaius Point by Aaron Dembski-Bowden

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.

A short story from Legends of the Space Marines.