Emhyr var Emreis

Few names in the Continent's history arouse as much terror and respect as that of Emhyr var Emreis, Deithwen Addan yn Carn aep Morvudd - the White Flame Dancing on the Graves of his Foes. Emperor of Nilfgaard, lord of Metinna, Ebbing and Gemmera, sovereign of Nazair and Vicovaro, he was ruler of half the civilized world and aspiring conqueror of the other half. He was a personage whose deeds and decisions shaped the fates of whole kingdoms and populations.

What then could he possibly want of a simple witcher?

The emperor clearly and succinctly laid out what he wanted. His daughter and Geralt's ward, Cirilla, was in great danger, for the Wild Hunt was on her trail. Geralt, a superb tracker linked to Emhyr's daughter by the iron bonds of Destiny, stood a better chance of finding her than anyone else in the world.

Thanks to Geralt's efforts, Emhyr finally had the chance to talk to his daughter face to face after long years of separation. Geralt doesn't know what topic was broached during their conversation, save that Ciri stormed out of it in a visible huff.