The two had a rivalry for a long as they could remember, from small quabbles over toys as children, to his, a fight to the bitter end put in the field. For Brynden, the eye was only the latest of the issues he had with his half-brother. For the woman he tried to take, for the brother he DID take, Brynden burning comtempt of Aegor ran deep, and he was sure Aegor felt the same way about him.
It was for this reason that Brynden would not surrender to his hated brother's onslaught. He knew that if his forces could hold on for just a little while longer, then the main Blackfyre army would eventually crumble to the two on one assault. He did not need to win, he just needed to last until Aegor lost.

As Prince Baelor and Gareth the Grey began their own duel, Baelor could not help but notice the soldier up on the hills. No longer did they wear the Targaryen banners. Instead they wore the banners of rebels. Brynden had been defeated, and now Maekar was dangerously exposed.
"CHARGE!" Bittersteel bellowed, signalling the Blackfyres final gambit.