Byron Mallister

Byron (469 AC - )of the House Mallister is the current Lord Paramount of the Riverlands and Lord of Seagard.

Background
House Mallister was the last remaining noble house in the Riverlands to practice the Faith of the Seven, meaning they were largely isolated from the other houses, rarely visiting their overlords, House Frey. Byron's father would be killed by a R'hllor mob right before the Iron War, causing Byron to have a hatred for that religion.

The Red Spring
Byron holds his coronation to become the new Lord of Seagard, as his brothers Addam Mallister and Rodrick Mallister watch. Byron and Addam are thick as thieves, and during a feast they are surprised by the appearance of King Ryman Frey, who offers Byron the position of Master of War for the Kingdom of the Trident. Byron graciously accepts, though afterwards he tells Addam he hates Ryman due to his zealous support of R'hllor.

The Typhoon of Steel
As Master of War, Byron tries to help Ryman design a war plan to defeat the Lannisters. With the Lannister army having a strong base at Harrenhal, Byron knows they need to move fast, so he sents a small host under Addam to take the Crag, hoping that Tybolt Lannister and Patrek Westerling take the bait and move their host around the mountains, giving the Freys clear passage through the Golden Tooth. The ruse fails a host raised by the Crag's castellan, Arton Hill, repels Addam's advance. Addam regroups with Byron.

The Frey and Lannister armies clash at the Battle of the Golden Tooth. Despite being outnumbered, Patrek manages to defeat Byron, and Rodrick is killed in the battle. The Frey host retreats back to Riverrun, and Byron blames Ryman for the death of his brother.

The Lion's Dawn
Byron meets secretly with riders from House Lannister, who offer Byron the position of Lord Paramount of the Riverlands in exchange for overthrowing Ryman. Byron agrees, and convinces Addam to go along with his plan.

Ryman arrives at Riverrun, but Byron maneuvers the Frey army into allowing the Lannisters to encircle and besiege the castle. Ryman suspects something is up, and sends his Spymaster Artos Rivers, to spy on Byron. Artos discovers Byron in the middle of the night opening the gates for the Lannister army, who proceed to occupy the castle. Addam is forced to kill Artos, and Byron and his Captain of the Guards, Ironside Hughs, capture Ryman and hang him. Byron declares himself the new Lord of the Riverlands, and swears fealty to Arthur Lannister.

While the Mallister army is sent to besiege the Twins, where Ryman's wife and most his family reside, Ironside is sent to kill Ryman's heir Edmure, who had escaped and fled to the Bay of Claws during the Sack of Riverrun. While Byron returns to Seagard, Addam is given Riverrun.