House of the Dragon has confirmed its most significant departure yet from George R. R. Martin's source material, with Season 3, Episode 4 revealing that Helaena is pregnant with a third child. In George R. R. Martin's book Fire & Blood, Helaena and Aegon's youngest son, Maelor, was present for a notorious attack on the royal children by the assassins Blood and Cheese, but the character has never appeared on screen. His absence, combined with Helaena's pregnancy reveal to Alicent, means the show has now moved entirely off-book, since in the source text this third child was born much earlier and under different circumstances.

The change raises fresh questions for viewers, chiefly around who the baby's father is. The straightforward assumption is Aegon, Helaena's husband and father of her children in the books, but the show's timeline complicates this: Aegon was badly injured in Season 2 and has said the injury will prevent him fathering more children, while his slow recovery suggests considerable time has passed since the Battle of Rook's Rest. The series has not clarified how far along the pregnancy is, only that Helaena has managed to conceal it, leaving the paternity question deliberately unresolved for now.