The grumpy one WAS very "alpha", so it's perhaps more a personality thing.
Being in season is the time when they are fertile; it lasts about 14 hours, during 2 of them they can be impregnated. They do not have a period like we humans. Any sign of blood needs to be checked out, as it is illness related.
With girls, you should have no problem with fall-outs or fights; they can squabble a bit occasionally, but that's about it.
Whether they will cuddle up together depends on the personalites, but it's more likely with girls than boys.