You pull out the water skin and swing it around as the vamp launches herself out of the crates. You manage to slap the leather pouch against her cheek and she hisses with pain. However, it's not nearly enough to deter her and she tears the weapon out of your hand before tossing it to the ground.
Your window of opportunity slams shut with the snap of her jaw. She sinks her teeth in and pulls with desperate thirst. She growls with disappointment when your weakening body fails to produce a steady flow of blood for her. So she bites at another patch of flesh in hopes of a more fruitful vein. Again she's disappointed and again she seeks another spot, leaving a vicious trail of marks along your skin.
With each new bite you feel yourself taking one step closer to an eternal darkness, one that is both terrifying and comforting. Soon you can't even feel her sucking the blood from you. You only have a distant impression of her mouth upon your skin and your vision blurs the world into a dreamy landscape.
The last thing you see is a heavy furred body rising up upon its haunches and grabbing the vampire in his jaws. All the blood drained from your body to restore that vampire's powers and it's gone with one clench of the wolf's impressive teeth.
Despite her being an enemy, you die with a strange sense of regret, feeling you lost your life in vain.
***
You've found one of the unsuccessful endings for this branch of the story... Why not go back and try a different weapon to use against the vampire?