It was hard for Dean to decide what part of Cas was his favorite... There was the obvious- his eyes (which seemed even more intense now that Dean knew exactly the reason Cas stared at him so intently), his lips (which alternated between soft and rough, depending on the mood of their kisses) and, well... other parts. But apart from all of those, Dean liked Cas' wrists. They were angular and slender, skin curving perfectly over the bones and tendons, leading to the hands that touched him in ways that made him shiver and his nerves thrill. It was Cas' wrists that he loved to kiss in the mornings when they awoke in each other's arms... when they were both too warm and content to get up, or in fact think of doing so.
Cas' favorite part of Dean was a bit easier to decide. Cas, of course, loved every bit of Dean. He loved his eyes and his freckles... his lips, and arms, and hands... but if he was honest with himself, Cas' favorite part of Dean was the curve from his neck to his shoulder, the perfect spot to rest one's forehead when sleeping. Not that Cas really slept. He tried, but all that really happened is that he slipped into a sort of timeless stupor from the hour that Dean fell asleep beside him, to when he could feel the man's lips tracing softly over his wrist and hand. He spent those long hours in that daze, simply breathing in the familiar scent of Dean's skin, feeling the rise and fall of his chest, and the steady rhythm of his heart.
They still hunted. They still rode around in that shiny black Impala with an arsenal of weapons in the trunk and Sam in the front seat. They still fought monsters, and demons, and ghosts. The world wasn't perfect and safe. But they were happy. Truly happy.