At the end of S1, the Khalasar that remained to see her walk into the fire and emerge unscathed banged with her for life. The ones that left left because Drogo died of an infection; if he had been killed by another Khal in front of them, they likely would have followed that dude.

So this time, not only did she kill the Khals in front of everyone, she did the impossible and walked out of a damn fire with not a mark on her. If you make your life following the strongest dude you see, surviving a fire is pretty damn strong.