Vampire Faction -- The Gift
The Elder Scrolls V: Skyrim - Dawnguard Walkthrough and Guide
by CMBF 
Vampire Faction -- The Gift
When you talk to Vingalmo again he tells you that he has learned that you are married -- and he wants you to turn her into a vampire! This flags the quest THE GIFT.
Turning your spouse into a Vampire for their protection
This is basically the same quest as the one you just did, except your wife is the target and not some unknown character. So when you are ready head home and cast Vamipre's Seduction on her, then feed and you will have completed the required steps for this quest.
After you turn your wife return to report your success and he is pleased. I did not receive a reward for this quest so perhaps there is not one -- either way reporting in ends the quest THE GIFT.
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When you change your spouse, are their eyes supposed to change into the kind of vampire eyes you have?
does your spouse go to castle volkihar when you complete this quest?
I do not believe that you can reverse turning a spouse...
Any "spouse" can be turned. I just wonder if this can be reversed?
Can Camilia V. from Riverwood be turned if she is your wife?