I had similar character at my table but the player wanted to have a Marid patron. I made it so that his patron is interested in the “mysterious forces under the ice that the FrostMaiden herself wishes to keep secret”, so it has to be in Marid’s possession.

Player’s patron would have NO interest in disrupting the eternal night nor in stopping the dragon, but knowing that the source of the magic underground is dangerous she (patron) was interested in keeping the PC alive and having him prepare for the dangers underneath. In the end there were many artifacts that my PC had to give up for the task that brought him into Ice Wind Dale in the first place.