House of the Dragon: What in the world is Alicent going to do at Harrenhal?

House of the Dragon Season 3 has made several huge deviations from George R.R. Martin's Fire and Blood. It cooked up Ormund Hightower's (James Norton) entire plan to crown Daeron Targaryen (Benjamin Evan Ainsworth) from scratch, and it gave Nettles' book storyline to Rhaena Targaryen (Phoebe Campbell).

Now, though, it unleashes what could be its biggest change yet: sending Alicent Hightower (Olivia Cooke) to Harrenhal.

Alicent spends the majority of her time onscreen within the confines of the Red Keep. In fact, starting in Season 2, every time she has left the Red Keep has marked a major shift from House of the Dragon's source material. She met with Rhaenyra in the Grand Sept to discuss peace efforts, took a cleansing swim in the Kingswood, and snuck onto Dragonstone to offer Rhaenyra a game-changing deal. None of these excursions are in Fire and Blood. Then again, House of the Dragon has often played fast and loose with Alicent and Rhaenyra's book dynamic, complicating it nicely by making them childhood friends.

The show's latest installment in its "Let Alicent Hightower Go Outside" initiative doubles as an assassination attempt. Rhaenyra knows that she needs to take Aemond Targaryen (Ewan Mitchell) out. She also knows that he's holed up in Harrenhal and separated from his dragon Vhagar, offering her the perfect chance to strike.

However, just because Aemond is vulnerable doesn't mean he's unstoppable. Rhaenyra realizes that if she sends many soldiers to take him out, he can just flee again and become more untraceable. Instead, she decides to send just one sword, accompanied by someone he trusts: Alicent. She'll lure him into a false sense of security, and then the assassin will dispatch of him.

This whole storyline is a show-only invention, as Alicent remains in Red Keep mode from the moment Rhaenyra takes the Iron Throne in Fire and Blood. So, there really is no way of knowing what fate awaits Alicent at Harrenhal. On the one hand, she knows how unpredictable Aemond is, and she's willing to do anything to protect Helaena. Will that be enough to make her stand by as one of her sons — granted, the creepy son who did kiss her — is murdered? Or will she try to warn him?

I'm leaning towards the former (again, the Aemond kiss clearly shook Alicent), but there's a big wild card in play: Alys Rivers (Gayle Rankin). The witchy guardian of Harrenhal has ensnared Aemond by weaponizing his mommy issues and showing off her clutch of dragon eggs. She's also proven that she has some sense of the goings-on around Westeros, based on her knowledge of the Battle of the Gullet in episode 1. She'll likely be able to sniff out Alicent's true purpose at Harrenhal from miles away. And if Alicent makes an enemy of Alys, she'll definitely wish she'd have stayed cooped up back in the Red Keep.

House of the Dragon Season 3 is now streaming on HBO Max, with new episodes premiering Sundays at 9 p.m. ET on HBO and HBO Max.