Olld-Onne posted...
You have to side with Hermaeus to complete Dragonborn. All DLC is considered canon unlike the faction questlines. The DLC itself shows you how Hermaeus already trapped a Dragonborn in his realm.
Mora's a little blurry. Even though he acts like you're doing exactly what he wanted you to all along, and says you're his champion (regardless of whether or not you agree), you can technically complete the entire questline without ever agreeing to serve him (even giving him the secrets he asks for can come across more like a trade than fealty). And Neloth will tell you afterward that there is no lingering influence from Mora on you.
But you've literally and explicitly sold your soul to Nocturnal. You cannot finish the Thieves' Guild quest without doing so.
You're also bound to Sithis and the Night Mother, and may have a connection to Hircine (if you're still a werewolf). All of them seem to have more of a claim on you than Mora does.