All of these grendels are based upon the Multi-Colored Grendels by Slink. Among other things, this means they can breed and have flight-or-fight genes.
Aqua GrendelsOkay, not "Aqua" grendels per say. These are my interpretation of an aquatic creature if such a thing were truly possible in Creatures 1 (which lacks water). Among other things, they're cold-resistant and have a better immune system.
These grendels are basically reverse Shee. The Shee is a warm-blooded creature that can suffer from hypothermia. The Erzan Grendels are warm-blooded creatures that can suffer from hyperthermia - that is, they can overheat if their internal cooling system malfunctions. That's their main gimmick, although they're also slightly more placid than the standard grendels.
They're my least favorite of my breeds, mostly due to the fact that they're very sloppy by my current standards (among their other features: immunity to glycotoxin. Yeah, there goes all the challenge of keeping one of these buggers...).
Scortch GrendelsThe Scortch Grendels feed off heat. If kept in a hot area, they typically won't need to eat. They're also quite resistant to heat. However, coldness has the opposite effect - it drains them of nutrients, makes them extremely hungry, and sends them into a state of sluggishness and torpor. In fact, cold is practically lethal to them. As a result, they're actually a bit more difficult to care for than standard grendels, as disease has the potential to inflict them with cold. If not cured rapidly, they'll die within several minutes.
I also tried making them slightly more aggressive than the standard grendel, but I don't think it worked out so well in practice. But oh well.
These grendels get most of their nutrition from physical contact with other creatures. As such, they spend a lot of time attempting to get other creatures to touch them - either through slapping or snogging. Despite this, they are pretty friendly and social (provided the Grendel Friendly COB is installed, that is).