Sepulcral Warriors are a successor chapter to the blood angels. Darious, the founder, managed to find a DNA sample that was similar to that of Sanguinius; however it had been modified and the DNA was not as potent, there was no blood thirst but the space marine would be weaker.
Darious knew that if the DNA were found then it would be destroyed, to preserve the Gene he inserted it into ten progenoid glands, however none of the ten space marines developed the wings.
Darious locked himself away within his lab, trying to figure out why it did not work. Years passed and slowly the selected space marines died and the gene seeds were put into new space marines, as ordered by Darious. in the second generation strange things happened. One of the Space marines, Markus, had an unsatable blood lust and always charged the enemies, this one died when he charged a Khorn Blood Thirster, his last act was to throw himself at the daemon with a vortex grenade in his hand. three of the other space marines fell to chaos and their gene seeds destroyed. One of the space marines started to develop wings, however the wings were bat-like and could not carry the weight of the space marine, this space marine was dissected and destroyed also.
In the third Generation of space marines there was one who was faster, stronger and smarter than the others, he was named Sanguin, as expected this space marine grew feather wings.
Sanguin is a master tactician, he greatest feat was a battle against a tyranid hoard. Choosing the site on which he would engage the hoard he was able to wipe them out with one shot. He has chosen a flat open area which had a series of caverns beneath them, in these caverns he ordered explosives to be packed. The four squads of Imperial guards which had been assigned to him had not been told this, he ordered them to make a line across the field and told them that the space marines would Flank the xenos hoard. When the tyranids were almost upon the guardsmen Sanguin detonated the explosives, killing the hoard with minimal loss, only four squads of guardsmen to be precise.
P.S Hope you like the back story to this guy ^^