Robert was already changed and was starting a very physical warm up. He was in superb shape, despite being older than Brian. He had never lost a challenge to any of his men, and he wasn't about to start now. He knew sometime in the future he would be bested, but it wasn't going to be tonight. His bigger concern was that he knew how Brian's mind worked. He knew Brian wanted to either redeem himself for not being able to take the cruciatus earlier in the day or to find out why he couldn't handle it. He knew Brian was going to push him hard tonight. Brian was already looking for blood--his own. And Robert needed to wear him out more than hurt him.
Robert engaged him in, first, a physical fight. He made sure he controlled the pacing of it. He was not going to let Brian get what he wanted too soon. Robert was not holding back on any punches either. When he hit him, he hit him as strong and hard as he would any assailant. He knocked Brian on his butt a couple times, but Brian always sprang back up again. At one point, Robert heard a sickening crunch as one of his punches broke Brian's nose. Brian didn't even seem to feel it. Robert knew Brian's adrenalin and his endorphins had kicked in and he wasn't feeling much of anything. Brian got in a couple of good blows in Robert's jaw, and Robert knew full well it was going to be coal black when it finished bruising.
It seemed like the contest was going to go forever. Then Brian hit Robert right in his cheekbone, and Robert felt pretty sure Brian had broken the cheekbone by hitting it at just the right angle. It distorted Robert's vision for a moment, but he heard Brian coming at him again. Unable to see, Robert fired a wandless stunning spell at Brian. It threw Brian across the room.
Brian rose with his wand in his hand. Robert was regaining his vision in just enough time to draw his wand. The level of danger, Robert knew, just escalated. Now magic spells flew back and forth, and now they were drawing blood. But Brian was clearly getting the worst of it. Robert was using incredible restraint with his friend. Brian had thrown a few sectumsempras, even, trying to provoke Robert into returning deadly fire, but Robert refused. he merely blocked the spells. Finally, with both of them getting exhausted, Robert threw a spell that caused a wound to Brian's midsection. The blood flew everywhere.
"Enough!" Robert roared. "I will NOT use a cruciatus on you, no matter what you throw at me! It's over! I have no desire to operate on you tonight! Stop now while you're ahead." Both men had to now take a moment to breathe.