Daenerys Targaryen becomes the owner of three dragon eggs gifted at her wedding to Khal Drogo: one dark red, one blue/green, and one sand yellow. Illyrio Mopatis believes time turned them to stone, but Daenerys discovers otherwise.
This sand yellow egg will become the dragon Viserion. Dragon eggs hatch in roaring flames, with another creature sacrificed - "Fire and blood," the Targaryen motto.