Soulmates found one story at a time.

Surma is a gigantic dog with grey fur, upright ears, and a snake for a tail. He can turn people to stone, has an earth-shaking bark, and guards the Underworld of Tuonela

Viktoria‘s grandparents, Tuoni and Tuonetar, are the god and goddess who run the place. They regularly indulge in Beer of Oblivion, and when their hangovers are bad, Surma gets evicted. 

When he runs amok in the world, the Maidens of Pohjola  are responsible for catching him.