Cold

There was much to fear in the brutal cold (everything attracted to the warmth of blood and movement just for starters), but the yetis had developed an affection for humankind that was part curiosity and part junk food scraps left out in bins. They were protective of these soft and mostly hairless tinies - what with their feisty frailness and ability to look darling in the face of doom. Really, it was their ridiculous tenderness that sealed the deal - the pretentious puff and bother of them active at the same time as their selflessness and generosity. Irresistible. The yeti would not allow (most of) them to be enslaved or eaten; they were just too precious for words ... and they made a mean burger and fries combo.