Bright-Scales, the oddly-colored protagonist of my currently-unfinished quest mod project for Oblivion, Vampires Guild, is visiting Skyrim. He can be found in Winterhold staying at the Frozen Hearth Inn.
Completing his short quest will allow you to take Bright as a follower. The young vampire boasts a leveling Vampiric Drain spell and a hood for sunny weather, and he'll also cast the Muffle spell on himself when he begins to sneak. In combat, Bright can summon powerful atronachs and uses strong defensive spells, such as healing, armor spells, and wards, though his Destruction magic -- ice and lightning spells -- is somewhat on the weaker side. If a vampire follower isn't to your liking, Bright can be persuaded to cure himself.
Bright has unique dialogue spliced together from existing voice assets, and has location and set piece commentary as a follower, as well as a little ambient dialogue about his trade and current goings-on in Skyrim when spoken to when not following.
As he uses a vanilla voice, Bright is integrated into Dawnguard and Hearthfire content (though he cannot be made a steward), but as Keith Silverstein did not return for Dragonborn, Bright cannot make use of any Dragonborn-specific dialogue.
Bright can be married if you wish; he simply needs to be taken as a follower once. Although in Vampires Guild's story Bright was homosexual, here he can be married by either sex.
There's a compatibility file for Change Follower Outfits included in the download.