Troi

Troi was a Dream Master from the parallel universe that is only featured in "Dream Master" (2017), a short story set in the Elsaverse. He is the one that brings the "Morpheus" to Elsa's realm, and probably who started her lineage after sleeping with Mary.

Personal
Troi gets in Sangrive's world back in the 17th Century, through an interdimensional portal, while trying to escape from Xara after violating Morland's dreams. He's found badly hurt by Mary, a young widow who lives alone in the woods near the spot where Troi has appeared, and who takes care of his wound. That night, he uses his Dream Master abilities to enter Mary's dreams and thank her for her kindness. He also tells her about his origins and skills, confessing that he comes from another realm and that his fate is sealed, as he's being pursued by a legendary enforcer he would never be able to escape from. After flying a bit in their shared dream, she asks him to wake her up, as she's feeling very aroused by his presence. They make love in Mary's cabin, and Troi shows her that sex can be pleasurable for women too. The next morning, Troi leaves his cat, Hunter, and his "Morpheus" book with Mary, and then come back to the portal spot to wait for Xara. When she arrives through a new portal, Troi tries to warn her about how king's plans don't end well for them, but she doesn't listen and just orders him to follow her. According to Xara, the punishment that awaits Troi is death.

Powers
Troi is a Dream Master. As such, he can enter other people's dreams and communicate with them, among many other things. In the dream he shares with Mary and his cat, Hunter, he tells her about his origins in that other realm and why he's injured. He also teaches her his language, in order to be able to communicate with each other, and says he's healing himself while sleeping. In that dream, Troi can also listen to Mary's thoughts, learning that she finds him very attractive.

Miscellaneous

 * In Saving Chloe (2018), it's stated that Elsa's origins can be traced back to the parallel universe, although nobody knows what those origins actually are, only that it must have happened many generations ago. Dream Master seems to imply that she's a Troi's descendant.


 * Troi seems to know that time runs faster in Mary's realm than in his. This detail is apparently lost on Xara, who in a non-canon path in Saving Chloe mentions an episode of her coming to Sangrive's world and not dutily reporting how time moved faster than in their original realm.