My head cannon endings for all the Hilda cast post finale (Spoilers for season 3)
Astrid
She remains in her home, never moving away. However she makes sure to visit Hilda often, which has become easier now that she's learned to fly again. She also doesn't get to lonely as she invites the Pooka to like with her and helps him practice shape shifting. When she dies she is buried where the fairy mound once was to be closer to her family.
Raven
He travels the world but always returns to Trollburg, on cold winter nights he joins Hilda and her family for tea and games, maybe the yule lads join in too. On his travels he spreads the story on Hilda far and wide even long after she's gone.
Tryla & Baba
They remain at the mountain most days but do ecompany Hilda on adventures during her weekly visit. They still live there long after everyone else is gone, telling tales of Hilda to the next hundreds of generations of trolls.
Anders
He continues living in Trollburg, working on wall and city maintenance with the bellkeeper. He never gets back together with Johana but he does try and be a better dad to Hilda, including taking her on that camping trip.
Johana
Begins selling her paintings to people, she also starts painting things from her and Hilda's adventures, including the Fae Ilse, which she still thinks about often. When she dies Hilda burries her at the fairy mound with Auntie Astrid, but she keeps a lock of her hair in a locket. One day, in the far future when Hilda has finally moved on she hangs that locket at the remains of the cabin.
Tontu
Just keeps doing what he does mostly. Going on adventures with Hilda occasionally but mostly keeping to himself. He remains in the house for a long time, even after Hilda had died.
Alfur
Keeps writing reports for the northern counties but he also begins working with Gerda and the safety patrol, his days are busy but that's how he likes them. When he dies, if elfs even do, he would be given a funeral pyre by the lost clan and Hilda returns to the northern counties to scatter his ashes.
Louise
Would go on many more adventures with the trio and would start to develop a crush on David, one that David would reciprocate. She would eventually become a wildlife photographer.
David
Started researching entomology and now runs an insect focused wildlife centre near the sparrow scout building, enjoying a more peaceful and quiet life than most of his friends. He also assists the linworm in a construction of a new garden on sparrow scout property, sometimes the two of them and Louise have tea together. He was the first to die out of the four and was buried in Trollburgs graveyard, later Louise would be buried with him when she died.
Frida
Finished her training and became a fully fledged witch. She would take over running the Trollburg library from Kaisa after Kaisa was appointed to the witch council. When they were teenagers she and Hilda started dating but they never decided to get married.
Hilda
She still goes on adventures in her teenage years, it wouldn't be Hilda if she didn't. She and Johanna also practised flying with their fae magic. She always makes sure to keep in touch with Astrid and Victoria. She continues to paint and make music and becomes a freelance artist like her mum. Twig also grows big enough to ride when he gets older. She lived in her apartment in Trollburg until her death. She and Frida were buried together at the overgrown remains of the cabin
Woodman
He's still there, deep in the woods. even after everyone else has long since died, perhaps he tells the tales of a mysterious blue haired friend to spirits to the passersby.
Or perhaps he would tell you that if you walk deep enough into the woods, you could find an old forest glen where a cabin once was, and you can speak to her spirit yourself