Marcel Artaud, a Mages Guild alchemist in Firewatch, asks a vampire player to donate up to three samples of their blood as a rare ingredient for his alchemical experiments. After each iteration, you lose some of your current health, then receive a reward:
ModCurrentHealth -25, reward is a bunch of potions
ModCurrentHealth -50, reward is several damage-dealing scrolls
ModCurrentHealth -100, reward is a Drain Health amulet
Maniel Sylbenitte in the Old Ebonheart Mages Guild wants to obtain one of the four powerful Scrolls of Immobilizing Domination (Paralysis on self + Command on area effect) from a vault in Roa Dyr. Seeing a vampire as a perfect instrument for illegal jobs, and considering they are immune to paralysis, he wants to use a vampire player to achieve his goal. Simple fetch quest.
Reward: three other scrolls and everything else you can find in the Roa Dyr vault.
The scrolls don't exist in Roa Dyr and should be created and placed by the claimant.
In the Grey Lodge tavern between Menaan and Arvud, there is a mercenary whose trade caravan, along with a merchant and another guard, was entirely wiped out by a single vampire. As the only survivor, he lost his mind and started to believe he was chosen by that vampire for a reason unknown to him. When a vampire player meets him, he asks the player to track down that vampire to find out why he was left alive.
Vrashammu, an ancient Baluath vampire in Madalvel Ancestral Tomb, is experimenting with mind control magic on mortals to create a slave army. She's the target of "Lost in Transit" quest, where she kills a young Redoran member from Bodrum. The truth is, she killed him in self-defense because her Command spell went out of control and the Redoran turned against her.
Due to vanilla dialogue filtering, all TR Morag Tong masters can hand out vanilla writs and reward you for their completion as long as the related topics are available. It doesn't work vise versa and would require adding a lot of new dialogue in all TR writs.