In books Emhyr's father was murdered and Emhyr himself was cursed into a monster by an usurper to take over Nilfgaardian throne. Emhyr married Pavetta, princess of Cintra

princess of Cintra

Cirilla Fiona Elen Riannon (better known as Ciri), was born in 1252 or 1253, and most likely during the Belleteyn holiday. She was the sole princess of Cintra, the daughter of Pavetta and Emhyr var Emreis (who was using the alias "Duny" at the time) as well as Queen Calanthe's granddaughter.

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what resulted in birth of Ciri. The curse was lifted thanks to Geralt of Rivia.

Why did Emhyr go by Duny?

After an argument on board, Emhyr pushed Pavetta overboard, and the only thing left was to fake his death as Duny and return to Nilfgaard as Emhyr.

Does Duny become Emhyr?

But Season 2 indulges properly into their story. The season finale came with a massive jaw-dropping moment when it finally revealed the true identity of the formidable White Flame. And it is Emhyr var Emreis (also known as Duny), Ciri's father.