Bruce had taken his time their first time. He had wanted to savor the feeling of sinking into Tim and the way his body clenched around him. He doesn't feel a sense of urgency now, but there's something in him that doesn't want to go slow. That wants to slam into Tim so he'd remember and understand there'd never be anyone else to fill him up like this. None of them would ever slot together as perfectly as they do. Tim would never let anyone else try.

The thought has Bruce putting his hands on Tim's shoulders, bracing against them as he pushed and pushed into Tim until their hips met.

He groans when he is in at last, breath hot against the back of Tim's neck. Bruce kisses him there. Once then a second time.