From the looks of those short jaws, your Orthrus must have a powerful bite (typically short muzzles are seen in strong biters like short-faced bears, hyenas, and pitbulls). Other factors play a role as well such as jawbone density, tooth structure, and muscle mass.
But overall, this beast's bite is WAY worse than his bark! Can't wait to see Humbaba.
Nice. I like how you have it split down the middle with the colors. I usually don't like that style because it comes off looking weird but you pulled it off. I like all the differences you can see fron one side to the other which is a nice change as well.
Yes, a lot of ancient cultures had the pantheons be all related to each other, what them all (usually) springing from the same source. With the Ancient Egyptians, it was a reflection of how the royal family married within the family in order to maintain the blood's sacred purity (to the point where some dynasties became so inbred so as to make hillbillies look normal). And yes, Isis, Osiris, Set and Nephthys were all sons and daughters of Geb the Earth and Nut the Sky.
Yes. Orthrus was a sort of cattle-dog working with someone named Eurytion to protect a herd of red cattle belonging to a giant named Geryon. As part of his 12 trials, Heracles (or, Hercules as he was later called in Roman mythology), killed Orthrus, Eurytion, and Geryon, and retrieved Geryon's herd of cattle.