Pilot Dan vs Series Dan.
I recently saw the pilot for the first time and was really surprised in the personality difference between Dan in the pilot and Dan in the series. I can't really say much without spoiling it but to see what I mean check out the pilot on you tube. Things have been switched for the series. In the pilot Dan is aggressive and confident and things go bad for Nathan but in the series nothing ever goes right for Dan and Nathan always lands on his feet.
Aggressive Dan's scene with 15Peter20 in the pilot is hilarious, I wish they'd kept that personality for the series.