Can someone suggest a place in Cyrodill where I can definitely find human blood? I need a couple of bottles for a mod I am playing. Obviously it is associated with vampires. Rather than search caves I am hoping I can buy it somewhere or find it easily in a building. Thanks if you can help.

What mod are you playing?

Human blood can be found here:

Vicente Valtieri's chest in the Dark Brotherhood Sanctuary.

The Pale Lady's secret room during the Lost Histories quest.

The Palace Sewers during The Ultimate Heist.

I don't have the mod in question, but I recall a thread here before with the same problem. The mod itself places additional supplies, and I'm not sure if they're the same item as the ones mentioned by Acadian (like there is more than one type of Vampire Dust - one specific to Bloodcrust Cavern). You may need to get the "right kind" for the quest.