In my personal category of lesser-known Norse deities, I included: Frigg, Hodir and Vidar.
Frigg (sometimes Frigga) and Hodir (sometimes Hodr) are likely better known than Vidar. All three are pretty cool cats. Well, not cats. That’s Freyja. She’s got a cart pulled by ’em. It’s also possible, according to some, that Frigg and Freyja are different aspects of the same deity. But not in my book! (Literally, not figuratively.)
Frigg is a Jotunn who marries Odin, the Alfather. The top dog. Why does she do this? I answer that. Odin ditches her all the time to go a’wandering. What does she do? I answer that. She sees the doom of all men, but never speaks it. How does that work? I answer that.
Hodir is the blind brother of Baldr. Both are the sons of Frigg & Odin. Why is Hodir blind? I answer that. How does he get around? I answer that. What does he do in the story? Same as in the myths. Read ’em if you want spoilers. In my book, hopefully I deliver on it.
Vidar is the son of Odin and Grid, a Jotunn. He’s nearly as strong as Thor, rarely speaks and does…some other stuff. Eventually. 🙂 He’s one of the characters who hooked my imagination and dragged me into writing. Contrary to the myths, he talks quite a bit in my book. “Vidar stared at him” would get a bit boring, after all.
Because less is known about these Aesir, I felt like I had more elbow room in developing them. But, since one of my goals was (and is) to be as true to the myths as possible, I took each mention of these Aesir and extrapolated upon them.
As an example, developing Frigg meant asking questions (as above) and researching women in Viking/Norse society. Not only did that help me visualize how she dressed — which was practically important for multiple scenes, but gave me an idea of gender roles and how Frigg could break them.
One such historical tidbit on roles helped me resolve a problem in Odin’s plot line (it’s a doozy). Since that happens at the end of Book Two, I had to foreshadow it — which meant writing several new scenes and making multiple references both in Book One & Two. Ideally, all of those look like worldbuilding so that resolution happens in the second book looks “surprising yet inevitable.”