Vampires: why does your character drink blood? Options

[Lady Saga]

I am having trouble with this one, and need some ideas. Why does your character drink blood? Why do they feed?

In Oblivion, becoming a Stage 4 vampire caused the majority of NPCs to be repulsed by our characters. They technically did not have to feed, but at least once the feeding was done, the NPCs stopped recognizing that our chars were vampires. This essentially gave our characters a reason to feed, at least.

But in Skyrim, this is no longer so (assuming Dawngurd is installed). The NPCs treat our characters with mild suspicion at best, but going from Stage 1 to Stage 4 does not actually cause any wanton sorts of behavior from the world.

So why does your character need to feed? What RP ideas have you all come up with?

[Darkness Eternal]

Interesting. Yeah, Raven can shift into a cloud of bats without going hideous vampire lord form. I am quite sure Molag Bal wouldn't limit that ability to the vampire lord, but then again, it seems that only form is the only one able to tap in ancient Night Powers of Blood Magic just like werewolves of certain lineages can tap in natural energies before magic was even known to be magic.