The halfway point in House of the Dragon means something. Time is running out for a time jump.

It was coming for a long time now. Since the first official images and trailers were released, it has been clear that an older cast would be replacing certain key players at some point down the line. It wouldn't make sense for everyone to look the same because the time jump between episodes 2 and 3 is a good 10 years.

The timing of the jump makes sense, but who exactly is being replaced, and by whom, is a mystery.

The actors who will be swapped in House of the Dragon are listed here.

Rhaenyra Targaryen

A side by side showing the same blonde female character played by different actors.

Milly Alcock is being replaced by Emma D'Arcy. Credit: HBO / Mashable composite

Rhaenyra Targaryen has become something of a fan favourite and it will be hard for some to swallow. The Princess of Dragonstone and heir to the Iron Throne will see a change in the second half of the first season, with actor Milly Alcock handing the dragon reins to actress Emma D'Arcy.

Alicent Hightower

A side by side showing the same red-haired female character played by different actors.

Emily Carey is being replaced by Olivia Cooke. Credit: HBO/Mashable composite

Although going from childhood friend to stepmother will probably do that, Queen Alicent is growing further and further away from the princess. Emily Carey plays a young Alicent for the first half of the series, but now the role will be taken up by Ready Player One and Sound of Metal star, who recently confirmed in an interview that the time jump hasn't done anything to repair things between Alicent and Rhaen

Laena Valeryon

A side-by-side composite shows two women with bright blonde hair, one younger, one older.

Savannah Steyn is being replaced by Nanna Blondell. Credit: HBO / YouTube / Game of Thrones / Mashable composite

Laena Velaryon is the oldest of the Velaryon children. Her parents, Lord Corlys Velaryon and Princess Rhaenys Targaryen, had a very awkward conversation with King Viserys when she was 12 years old. In episode 5, a few years later as a teen, she's played by SAVANNAH STEWARD, flirting with Daemon Targaryen at her brother Laenor's wedding to Rhaenyra, and now she'll be played by RED DOT.

It appears that Laena will have a major role in what's to come.

Laenor Velaryon

A side-by-side of two men, one in costume with blonde hair, the other out of costume wearing a suit.

Theo Nate is being replaced by John Macmillan. Credit: HBO/David M. Benett/Dave Benett/WireImage/Mashable composite

Laenor Velaryon is going to be replaced as well. The son of Princess Rhaenys and Lord Corlys, heir to Driftmark, and now King Consort to Rhaenyra, he's played by TheoNate in the first half of House of the Dragon. We couldn't find an image of what he would look like in the show, so you have to use your imagination.

Most of the key players include King Viserys, Daemon Targaryen, Rhaenys Targaryen, and Lord Corly.

The new House of the Dragon episodes can be seen on Sundays.