While hauling stone to form a nice, safe wall around my open magma vent, on of my woodcutters was attacked by a fire man. Her entire right side was burned, leaving her with yellow injuries on her right leg and arm. She managed to escape the fire man on her own power, but collapsed in a useless (but conscious) heap within 30 tiles of my fortress's main entrance.
... Then I saw the fire.
Due East of this unfortunate woodcutter, a fire imp had died. In its death throes, it started a fire that swept in a great circle around it. This fire raced towards the wounded Dwarf, and I thought, "Surely, she's a goner. She'll be caught in the brush fire, catch fire herself, and die."
One of the miners, recently set to medic duty (because nobody else seemed to be doing it, despite being set for it), rushed out to save the woodcutter. The miner wasn't the type to like helping others - in fact, she "would never go out of her way to help others." But she raced against the flames to save a woodcutter she was hardly acquainted with.
Just before the flames consumed the woodcutter, the miner reached her. Together the two ran through the smoke, and made it within the fire-proof stone before the fortress entrance.
It was a surprisingly heroic and well-timed move, and I was lucky to see it play out so.
EDIT: I wish I'd thought to record it once I saw the flames.