Pictures
(v5, p56) and surrounding pages. Note the curious red bit in the middle of one lens of his glasses.
The following were notes while the character was evolving. They do not necessarily represent the way it came out.
Prince of the town of Sturmhalten, just off Balan's Gap (v5, p48). Used to be a major Spark, but has lived quietly as one of Klaus' vassals in recent years.
Implicitly, we have reason to believe that Aaronev likes a good thrill: on (v5, p55), he asks for a fairly racy Heterodyne show and asks them to "tart it up". Indeed, on (v5, p56) we get to see quite explicitly that Aaronev can be dangerous to players who put on a dull show.
On (v5, p57), we are told that "they" have accused Aaronev of disloyalty -- I assume that "they" are the Geisterdamen.
We see, on (v5, p57-58), that the people of Sturmhalten are somehow particularly susceptible to Agatha's voice. Much later, they are described as, essentially, an odd sort of Revenant.
Aaronev is a member of an "Order", about which we don't know much yet, save the implication that he is somewhat tenuously their leader, and that they are probably dedicated to bringing back Lucrezia (v5, p69). According to Vrin, they are the "shadow knights", and they originally had a different purpose (v5, p81).
His full name is given by Tarvek on (v5, p96).
According to Anevka, Aaronev [collected girls with the Spark], presumably to try to implant Lucrezia's consciousness in them.
He is killed by Anevka on (v5, p69).