House of the Dragon has never been above changing events from its source material, Fire & Blood. In fact, that may be the reason George R. R. Martin isn’t the biggest fan of the show anymore. But with those changes comes a new opportunity: there is no longer a guarantee that what happened in the book will happen in the show.
Which is why dragonseed Ulf the White is such an interesting character. As of the Season 3 finale, he’s on a much different path than his book counterpart, and he might meet a much different end.