That was Nidhogg's 2nd mate as his 1st was the one that started the war. Um, I'm not sure what happened to Hasvaelgar's orignal babymomma. I dont think there is enough info out there. I mean for all we know Nid, Hasvaelgar and Ratataskor (sp?) had an open relationship. Or he had fun with one of Tiamat's off spring. We still havent seen either of the missing two of the seven. We do know the Allagans were holding a 2nd great wyrm just that one excaped. One of them is a loner if you go off their outside of the game lore. The other one again going off their outside of game lore seems to be a HUGE jerk and likes to build damn/forts in rivers.

Heck we don't even know who Middy slept with to get those 7 eggs.