Originally Posted by American Maid
Of course, Hela is a Jotunn. Presumably, if Loki is her son, he would not be her father
So she could well be full Jotunn, which would make Loki full Jotunn too. And that doesn't align with one of your other working hypotheses
Unless they make her Asgardian, instead of Jotunn. . . .hmmm!
well she's definitely not a frost giant (which would still resolve one of my issues, if she is his mother), and really they can make her whatever they want as far as being a giantess, or normal sized, or Asgardian or something else. Seems like it would be easier to explain Hela's existence in that way, then going the traditional route and trying to explain the hows and whys of all of that in the context of the MCU.
There is a story about how he'd get Hela to take his name out of the book of Hel when he dies (more than once I think), so he could return to the living world, can't recall at the moment if that's Marvel or Myths or both, but it's kind of cool and they could use that then.