Observed unusual traits in later-gen Grendeltails, of which Zen is one (note that he has some unique traits of his own and may not display every trait on this list as strongly as some othis Grendeltails):

- Continuing intense hunger for protein that is not apparently sated by eating proteinaceous food

- A connection between manky and hunger for protein that emerges in youth or adulthood but not before. Will tell othis Norns who express hunger for protein to 'maybe eat manky' and will obsessively consume manky class items if allowed access to it. Reaction to alcohol-containing fruits and the like is much less intense, so the connection is specifically to the concept of manky. Will drink large amounts while striking a characteristic pose, a little like the beginning to the Horny Dance or the pose they strike sometimes when slapped, but with no sign of being poisoned except for occasional slightly odd behavior (probably intoxication-related). Does not seem to get drunk in the usual way, but does exhibit some slight altered behavior if allowed manky. 

NOTE: Zen does not appear to experience this as strongly as some other Grendeltails. If instructed to 'eat manky', he will, and he will probably display the same behavior once you get him going, but he hasn't been one of the ones who dives on the manky as soon as they spot it. 

- Very resistant to death by slapping, but can starve to death or die of old age.

- Tends to prefer clustering with othis Norns to exploring; will generally not wander away from the group of his own accord. 

NOTE: Zen has a habit of walking back and forth over a short distance a whole lot. So he's not as intense a clusterer as some of the other Grendeltails. He still won't get TOO far from the group he's hanging out with, most of the time, but he does have a way of pacing back and forth a lot, often taking him a bit beyond the edge of the cluster, rather than just hanging close like the others do. 

- Highly fertile. 
NOTE: Due to Zen's peculiar pacing habit he doesn't pay as much attention to females as a typical Grendeltail male. He may still mate in your world, but you might have to use Cupid's Lyre or even order him to push norn if he doesn't kisspop on his own. He may be too lost in his own little world to mate alone. MOST Grendeltails are excellent breeders, but I have seen others born that are just too obsessive about other things to make time for kisspopping, and he might be one of them. 

- May occasionally exhibit some aggression, but not to extremes as a rule UNLESS kept with othis Grendeltails, in which case you will see the occasional massive slap-fight broken up by bouts of kisspopping. May not take much notice of being hit himself; probably very pain resistant in general but have not specifically tested this yet. 

- May sometimes develop weird fixations or do strange stuff in general, such as staring at a single Norn while saying 'eat Norn', or suggesting that a friendly Norn 'maybe hit Grendel'. These are things done by close relatives of Zen's, not Zen himself (in fact he was the Norn being stared at in the 'eat Norn' example), but the potential for bizarre behavior remains, especially since he's such a weirdo in other ways even by the standards of his... breed? Landrace? Not sure what I'd call the Grendeltails at this point. Lineage works best I guess. Point is, he's weird even by Grendeltail standards, so don't be surprised if he does weird stuff. 

I have not done a close survey of the Grendeltail genome, so thise may well be many othis mutations and weirdnesses I have not covered hise. Grendeltails are mostly feral; I leave them to wolfling on their own for long periods, albeit in a highly modified, agent-filled, docked world. Still, they have decent survival abilities on their own and are well suited to wolfling runs, if you don't mind them completely overflowing your world with eggs!