They haven't seen each other in some time, but a reunion won't occur under the best of circumstances for Brienne (Gwendoline Christie) and Jamie (Nikolaj Coster-Waldau) when they come to face-to-face at Riverrun on Game of Thrones.

Jamie is at the castle to try and convince the Blackfish (Clive Russell) to either surrender or face the Lannister army as they try to take it back for the Freys, who were given it after they murdered Catelyn and Robb at the Red Wedding. Brienne has arrived to ask the Blackfish to provide his forces for Sansa (Sophie Turner) and Jon's (Kit Harington) army to take back Winterfell from the Boltons. Now, the two former allies will come face-to-face, and Brienne will have to warn Jamie that if he stands in her way, she will have to make a move against him since she is now bound to complete Sansa's orders.

"Should I fail to persuade the Blackfish to surrender and to protect the castle, I will be compelled to fight you," she says in a preview clip for the Sunday, June 12 episode.

However, Jamie won't let himself be defeated, and he too will want to make sure he carries out what he was also sent to do, because until he does, he can't return to King's Landing, or Cersei (Lena Headey), and he wants more than anything to be back with the woman he loves.

"I love Cersei. If I have to slaughter every Tully who ever lived to get back to her, then that's what I'll do," he says.

Meanwhile, back in King's Landing, Cersei is preparing for a battle of her own, against the Sparrow and his followers, who have gotten Tommen (Dean-Charles Chapman) into their clutches to increase their power. Now, Cersei will decide to take them on in an effort to get her power back as well.

"Tell your man to step aside, or there will be violence," Lancel (Eugene Simon) says in the clip.

"I choose violence," Cersei says.

Game of Thrones airs Sundays at 9 p.m. on HBO.

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