Looking for a fic
It was a while ago that I read it, I think it was on ao3, but cannot be sure about that. The fic was complete, and had Tony saving Loki's kids and I'm fairly sure it ends up as FrostIron. I don't think Loki was even in the fic for a lot of the beginning, and might have only showed up when all the kids were rescued and living with Tony. I remember that he had to make a suit to save Jorgumander (I know thats not spelled right) from the ocean Jor is first seen as a giant serpent but still intelligent and helps Tony figure out where the binding on his prision are and when he was freed from his prison he became a young-ish boy and the suit also became a rescue pod, or was able to summon a rescue pod.
It might have started with Tony in the Arctic looking for Steve's plane, and noticing an anomaly in the ocean which leads to the discovery of Jor in his cage.