Dean

Your hair. Dean loves your hair and how it blows in the wind majestically. He just loves to play with it and is always braiding it. You always tease him of having a bigger crush on your hair then on you.

Sam

Your eyes. He loves to look into them and just stare for hours. Well not really hours because that would be a long time but you know what I mean. He loves the way they glisten and fill up with life when you start ranting on something.

Castiel

Your nose. He just loves the smallness of it and it's his hobby to annoy you by booping it.