At the end of Windborn Frostfire goes with Larksong and Starfrost somewhere else in Anok, and Star mentions that he didn’t think he’ll ever see Frostfire again. But Frostfire HAD to go somewhere. I personally think he went back to Mountain Herd territory, since that was the herd he was part of before he formed the Black Army. I think him crossing the ocean would be interesting........ Or maybe he went to the Trap? Idk