What causes thirst?
Basically, the lack of liquids in your body system. Actually.... A rise in plasma osmolality triggers thirst which in turn excites the hypothalamic thirst center. The hypothalamic thirst center neurons are stimulated when their osmoreceptors lose water by osmosis to the hypertonic ECF or are activated by angiotensin II, by baroreceptor inputs, or other stimuli.
Well right now, Thirst 4 just came out on August 9. If you can't find Thirst, The Last Vampire is the same series but individualized stories instead of three part combined books. Thirst One- The Last Vampire, Black Blood, and Red Dice. Thirst Two- Phantom, Evil Thirst, and Creatures of Forever. Thirst Three- The Eternal Dawn. Thirst Four- The Shadow of Death.