Taff had taken a while to fall asleep, his thoughts had jumble over themselves until he'd finally nodded off, not even aware of sleep creeping up on him. But he was exhausted, and so he slept through the night barely noticing the tight space in the bed between their bodies.
He didn't consciously feel his brother's hand moving down. He wasn't aware of Tristan's fingers on him at any proper level, but his body reacted regardless. Repressed hormones practically leapt at the chance, and Taff was hard in a minute flat. His breathing didn't even skip a beat.