opposites

"Come on, we all know she won't do that!" The group of friends sat around in the tiny circle they had made on the floor. Olivia just stared at her best friend in disbelief, 'how could he say something like that' she thought to herself.
"Actually, I'll do it. " Olivia bravely looked around as the words flew right out of her mouth before she could think twice.
"Wait, what?" David was completely dumbfounded. His best friend, who was the exact opposite of him, was actually about to ruin her perfectly crafted reputation.