Bloodfiend

The Bloodfiends are the disastrous attempt of a failed cloning procedure by the Blood Angels, resulting in hideous creatures utterly consumed by the Red Thirst.

History
In the aftermath of Arkio's manipulation by the forces of Chaos, with the Blood Angels teetering on the brink of extinction. Lord Commander Dante summoned all of the Blood Angels' Successor Chapters for a conclave on Baal following the near-disastrous Chapter civil war that nearly tore the Blood Angels apart. The Apothecaria was working on a radical new procedure to replenish the ranks of the Blood Angels in one swift stroke: the long-lost art of replicae, similar to the techniques that the Raven Guard had attempted during the tragic events of the Horus Heresy.

The experiments proved fruitless and Commander Dante would later order a halt on further attempts. However, Caecus disobeyed the order and secretly continued the experiments, prodded by an agent of the vile Chaos Space Marine Apothecary Fabius Bile. He was tricked into bringing Bile, who was disguised as a well-known Adeptus Mechanicus Magos Biologis, to Baal, mistakenly thinking the false "Magos" would help in cloning Space Marines to increase the Blood Angels' thinning numbers.

With the secret assistance of Bile, Caecus created a stable clone from his own geneseed, which he christened the "Bloodchild". At first it seemed to be huge success, but when it was matched against the combined might of Blood Angel sergeant Rafen and a Flesh Tearers sergeant, Noxx, the "Bloodchild" ultimately succumbed to the Red Thirst within a matter of minutes, and, after drinking blood from a wound it inflicted on one of its foe, transformed into a monstrous, vampiric mutant.

After that incident, Dante ordered Caecus to destroy his remaining "prototype" clones, but through Bile's manipulations, Caecus was duped, and only managed to create monstrous, mutant clone-Astartes dubbed as "Bloodfiends" who were consumed by the genetic curse of the Red Thirst. These creatures were a shattered mirror reformed in the image of a Blood Angel, but lacked any of the qualities that might be thought of as human.

The mutations that cursed the gene-seed of the Blood Angels had been enhanced by the machinations and Chaotic tech-heresy of Fabius Bile, and with each drop of blood they consumed, the thirst that dominated the Bloodfiends grew stronger. The mutants were set free by Bile from the confines of Caecus' laboratorium and began to run rampant through the sacred halls of the fortress-monastery of the Blood Angels. During their rampage, Bile managed to steal a glass vial that Caeucus had carried back from the Chapel of the Red Grail -- a measure of the mingled blood of a hundred centuries of Sanguinary Priests and the Primarch, the raw vitae of the Chapter.

The sons of Sanguinius led by Dante in defense of the Holy Sepulchre, where the Primarch's body was interred as the Bloodfiends massed together to attack were able to destroy the horde of abominations and erase the stain of Chaos from their midst.

Anatomy and Physiology
Bloodfiends began life as primitive creatures, although they became intelligent and stronger with the amount or potency of the blood they consumed. The corpses of victims left by the Bloodfiends were completely drained of all blood and other vital fluids.