Rafen is a Sergeant of the Blood Angels Space Marines Chapter who played a central role in both the Blood Angels Civil War and in defeating the machinations of the vile Chaos Lord Fabius Bile. Along with Chief Librarian Mephiston, Rafen is one of the very few individuals in the long history of the Blood Angels to have survived and mastered the genetic flaw known as the Black Rage--without having the soul bending weirdness that came along with Mephiston. Granted he only "mastered" it after an ancient relic called the Spear of Telesto burned it out of him and all the brothers in the field and Mephiston...who had fallen to it again because of Tzeentch and...reasons. And almost got promoted straight from a line brother to 5th company captain. James Swallow quickly realized this was dumb and averted away from that. Did I mention most of his notes for Blood Angels came from Matt Ward?
He was kind of a Mary Sue in the first book. He got better.
The Second Series of books is EASILY better than the first...in parts. Others are still full of fail. Like a "chapter civil war" between 1 company justified the need to call EVERY THRONE DAMNED successor chapter to give them their neophytes to rebuild.
That isn't to say cool things don't happen. They fight literal space vampires trying to drink the blood from the corpse of papa Sang. Divebombed a star fort into a planet just so they could get a submarine into the water. fought lictors inside a flooding hanger bay and rode on the outside of the submarine and fought a gigantic tyranid kraken beast so...It's not all bad.
luckily nearly all of James Swallow's other books are infinitely better. Including his excellent SoB novels and the seminal 'Flight of the eisenstein'