since u don't really want an happy ending. How about this
Jack wakes up from his coma and is with Elsa, everybody else end up feeling better but Hiccup is dead and Merida is mourning. there's a funeral. Merida can go away for a while so she can mourn and meet someone new. While Kristanna get a happy but sad ending cuz of merida going away so does Eugenzel and Jelsa. idk but that's all I got