Dean scowled as he started to step out of the car. He had seen a small animal dash into the road and he swerved, not wanting to hit it and dent the Impala. The stupid thing had run right in front of the car anyhow, so now Dean had to get out and put it out of its misery. Dean would make Sam do it (He hated killing anything if it wasn't hurting anyone.), but he was asleep, and Dean didn't want to wake him up.
Dean regretted deciding to get out of the car. The poor animal was yowling, for Christ's sake. As he headed around the front of the car, he realized he had hit someones cat. Not wanting to make it suffer anymore, he cocked the shotgun and aimed quickly, letting his finger push down on the trigger. After burying the body, Dean headed back to the car. He had left the door open when he went to kill the cat and was about to get in when he saw the tiny, gray fluffball sitting in the driver's seat.
It was a kitten, and Dean had just killed its mother.
"Son of a bitch."