Shepherds are smart, loyal, and independent - they need strong "leadership" or they become the alpha. Also very protective.

So not perfect for Sam...but I don't think Dean either - there are some great memes out there on leadership - and that Dean isn't necessarily a leader - but that isn't a bad thing - he is an amazing number two (I'm a totaly Dean girl so at first I was not pleased - but the authors make a very convincing case and it doesn't harm/hurt the awesomeness of the Dean!)

He could be a Bonobo. Just because...bonobo! But I still like the idea of Nana from Peter Pan.... :)