Arieh Luna is the current Supreme Grand Master of the Disciples of Caliban Chapter. He is a member of the Inner circle and one of only two privy to the whole truth of the Dark Angels, along with his counterpart, Grand Master Azrael.
Arieh Luna was believed to have been recruited from a civilised planet in the Segmentum Obscurus. Luna ascended to the vaulted position sometime in M41, after the death of Supreme Grand Master Videon Karlus. Supreme Grand Master Karlus was said to have nominated the relatively young Luna as his successor due to a quick rise from battle-brother of the 5th to captain in just over a century, a somewhat unheard-of feat amongst the unforgiving chapters. In his short time in command of the Disciples, he has gained renown as an expert swordsman, dueling many of the most famed bladesmen in the Imperium, each time triumphing. He has also honoured his Primarch by dueling Ragnar Blackmane of the Space Wolves in the traditional honour match between two champions meant to represent Lion El'Jonson and Leman Russ, the primarchs of the Dark Angels and the Space Wolves.[Needs Citation]
Arieh Luna is withdrawn and introspective, quiet and reserved. He will only let a select few whom he trusts completely past his guard, if he does not shun company entirely.
Very aware of small details, he has a tendency to be highly critical, both of others and of himself. He has a distinct tendency to brood on things, trying to piece together vast amounts of small details into a coherent whole and agonizing over anything that doesn't fit. He will rarely share his thoughts with anyone without encouragement, prefering to keep to himself unless specifically called upon. He may project unapproachability, probably by giving the constant impression that there is something very important preying on his mind (which may not be a false impression). Interruptions to his thoughts or other annoyances will probably make him suddenly irritable and scathing.
Despite being withdrawn and quiet, there is also a strong restlessness to Arieh Luna which tends to manifest on a small scale; tension, sleeplessness or a tendency to pace or fidget when deep in thought, which is most of the time. At best, keenly observant, an extremely sharp and logical thinker, self-sufficient and practical. At worst, overly critical, self-abusive, irritable, not forthcoming and unassertive, and unable to see the wood for the trees.