Cassandra here isn't in Solvunn, but I would love to have her and Thane meet in the Horizon somehow. She's.... not technically an assassin but she did murder the shit out of [SPOILERS].

She will be delving hard into the world and its lore and its history and things, too. Perhaps they can end up pooling their knowledge or something since they're in different places and might have different resources and variations of stories.