I plan to, but the right story hasn’t come along. In the meantime, I’ve drabbled out various versions of this, so you can take a peek at one of the little ideas I had in mind for it!
Seeing Sam in danger, Dean lunged for his brother, desperate to stop Sam from getting hurt or killed by the spirit when it attacked. His comparatively huge hand reached for the tiny hunter, intent on scooping him safely out of the way.
Unfortunately for them both, Sam panicked when he saw the hand grabbing at him and didn’t realize at first that it was just Dean. He flinched back, arms flailing in the air as he stumbled away. Dean didn’t have time to stop his lunge, the forward motion carrying him through. His hand brushed against the tiny body, sending Sam flying into the wall.
Sam hit the wall with a moan and collapsed into an unmoving pile.
Panicking, Dean blocked another blow from the spirit. His vision narrowed to tunnel-vision, unable to see anything but Sam, crumpled on the ground. Because of him. Because of Dean.