I felt the need to write a little more, so...
Dean grimaces as the cold peroxide touches his broken skin.
He shudders as he relives the hood of the Impala being slammed on his arm and
bouncing back up like it hit a piece of rubber.
Sam tends the wound on Dean's arm with the gentleness of a mother's loving
touch.
It reminds Dean of Mary, and how she cleaned his cuts and scrapes.
Sammy never really knew her, and yet is like her in so many ways it hurts.
It always catches Dean off guard, these moments.
He smiles up at Sam, thinking,
"Thank you, Mom, for my brother."