I don't see a need for a specific quest to introduce them. The others are all introduced 'naturally' during the course of the story and have a reason to be there.

A special quest out of nowhere just to introduce a Hrothgar character with no other reason to exist beyond saying "hi, I'm a Hrothgar, we'll be all over the place in a month or so" would seem pointless and forced.


That said, we still have the "Make It Rain" seasonal event in July, which would be an obvious place to fit in a non-permanent introduction.