During one of my journeys through the depths of the internet I just stumbled upon this archived page from the Spanish GW website, which features some cool background of one Captain Artemis, and also goes into some detail regarding the homeworld of the Chapter that initially recruited him - the Mortificators. I already knew about him from the rulebook still hosted on GW's homepage , but have read about his origins for the first time today:
Bits of it conflict with FFG's interpretation of the Deathwatch, but the differences aside I think it is a rather cool piece of fluff that may be of interest to anyone, be it players intending to play character from the same Chapter, or even GMs who may take inspiration from some of the missions mentioned in Artemis' record. Hope you enjoy!