Captain Avincus hails from a noble family on the world of Prandium in the Realm of Ultramar. He was recruited alongside his twin brother Gnaeus into the Ultramarines, where the twins served together for centuries. After more than three hundred standard years in service to the Ultramarines, the brothers faced a horror the likes of which none could imagine -- the Tyranids attacked Prandium. Gnaeus was slain, crushed by a Carnifex. Avincus was furious at what the Tyranids had done, and he was given the opportunity to strike back against them during the Battle of Macragge, where he fought valiantly amongst the Astartes of the Ultramarines' 3rd Company, seeing many of his Battle-Brothers slain during the brutal tunnel fighting. He was amongst those survivors who were chosen to join the 1st Comp