Harry Collett says he adlibbed 'Dracarys' in 'House of the Dragon' Season 3 pilot episode

Harry Collett finally got to say that iconic line associated with Targaryens: "dracarys," the dragon command to breathe fire.

In the pilot episode of "House of the Dragon" Season 3," his character Prince Jacaerys Velaryon rides his dragon Vermax to the Battle of the Gullet. He orders his dragon to burn enemy ships.

According to the British actor, he almost did not get to say the line.

"It's funny you say about the 'Dracarys.' Originally in the script, it wasn't in there. I just said it, when I was on the dragon," the British actor told GMA News Online in an online roundtable interview.

That surprised his fellow actor Tom Glynn-Carney, who plays King Aegon Targaryen.

"Oh, adlib? You? Legend," Tom told Harry. "You adlibbed 'dracarys.' That is class."

Incidentally, one of the first scenes of Jacaerys as a child (played by Leo Hart) in Season 1 is practicing the command on Vermax at the Dragon Pit.

Harry also talked about what it was like filming the battle scenes with his character on dragonback.

"We have this really cool stage called the V stage, which is like full of LEDs and you know, sort of make shifts where you are in that moment in time," he said.

"So when I was on the dragon, it would be like moving sky by me. So it sort of helped me immerse. And I think, I mean, we were saying earlier that the amount of wind machines is crazy."

He also had to film scenes on a water tank for the massive naval battle.

"I've never done anything in a water tank before and having a scuba diver drag me over by a little float when I've got like 16 layers on and I've got the wetsuit fit into a mantle," he said.

"House of the Dragon" Season 3 is now streaming on HBO Max. The series is about the conflict between two branches of the Targaryen dynasty, the Blacks and the Greens, for the Iron Throne. —CDC, GMA News