If you've ever played with the vanilla C3 grendels or any creatures based on their genome (such as CFE grendels, or Osiris Norns), you may have noticed they have a tendency to dance. That is, sometimes while they're doing something else they'll randomly strike a pose for a second before going back to whatever it was they were doing. It's most noticeable in creatures suffering from EES; while other creatures just tend to stay locked up in one position, grendels tend to twirl around and around until they're snapped out of it.
Since it's one of those things I find charming about grendels, I naturally sought the means to replicate it in other genomes. Since it also happened in creatures based on the vanilla C3 grendel's genome, I concluded that it had to be genetic somehow. However, what exactly was causing it was not so easy to figure out.
Since it involved grendels striking a pose, I figured that it might have something to do with the pose or gait genes...but nope. The actual poses and gaits themselves are more or less identical in both the vanilla norn and grendel genomes, and while there's some differences in the receptors that trigger them replicating these differences in a norn didn't result in a norn that twitched.
I could also confirm it had nothing to do with the brain, as all three species have the same brain structure in their vanilla genomes, and I also ruled out the grendel-specific chemical Grendel Nitrate (which reduces a creature's reluctance about hitting things, particularly other creatures; the brain gene responsible is actually present in all three species). So if not all of those, what was it?
My next guess was the involuntary actions (flinching, sleeping, etc.), as those also involve striking a pose sometimes. Grendels have two differences from norns involving those genes. One of them involved flinching from pain...but that wasn't it. The answer was in the other changed gene:
141 Different in file 1 201 0 Emb B MutDupCut 128 0 Organ# = 6, Creature, Sensorimotor, Involuntary action 7, chem=Air, thresh=77, nom=255, gain=255, features=Inverted Digital (0)
124 Different in file 2 201 0 Emb B MutDupCut 128 0 Organ# = 6, Creature, Sensorimotor, Involuntary action 7, chem=Air, thresh=77, nom=255, gain=0, features=Inverted Digital (0)
Involuntary Action 7 is drowning. This particular gene works by checking for the level of the Air chemical produced by a creature's body. Since it's set to Inverted, it triggers at low levels of the Air chemical rather than high levels.
In a norn (the first gene listed), both the nominal and the gain are set to max. Nominal can be thought as as the "default" level the receptor fires at if the associated chemical's level is below the threshold. Gain, meanwhile, can be thought as the level the receptor fires at if the chemical's level is at or above the threshold. And it's set to Digital to basically act as an on/off switch; a creature is either drowning or it isn't.
In a norn that's not drowning (that is, has a normal amount of Air in its system), the gain is subtracted from the nominal, and since they're both the same that's a value of 0 and thus the receptor doesn't fire. Should air drop below the threshold, it's not subtracted and the nominal value of 1 takes over, triggering the involuntary action.
In the grendel (the second gene listed), the gain's set to 0. So the nominal value is the only thing determining whether or not it's firing, and it's set to 1. So the receptor's always firing, regardless of the level of air in a grendel's system.
So that charming grendel twitch? That's what the drowning involuntary action looks like (if the grendel was underwater it'd also produce bubbles). So the twitch means grendels are always drowning. Which...isn't so charming.
Fortunately, the drowning involuntary action is separate from the actual breathing of the creature and doesn't impact their quality of life at all, so while vanilla grendels might technically be drowning all the time they're still breathing normally so long as they're not underwater or affected by anything else that could impact their Air levels.
The CFF and beyond changed how drowning works as part of the larger cycle based around lactate and pyruvate, so grendels based on those genomes shouldn't twitch any more. Which is fine, since CFF and beyond also added a stimulus gene to make creatures scared while they're drowning, so if it worked like how it does in vanilla grendels you'd get grendels that are scared all the time.
Suffice to say, now that I've learned what makes grendels twitch, I've decided that it's not worth reverting the changes to drowning in my standard genome, whenever I decide to start working on it. Which might be sooner rather than later; I'm a little stuck on my ettin genome at the moment, and I know I'm probably going to get a lot more use out of my grendel genome than my ettin genome.
Until the next one, folks.
