You were an angel of the Lord. You had known Sam for some time now. He and Dean were currently trying to stop Liluth from breaking seals. Little did Dean know, Sam was guzzling down demon blood and sleeping with Ruby, a demon, on the side.
One night, Sam had an encounter with Ruby whilst Dean was out. It left him feeling guilty, dirty, and used. He felt that way every time he slept with Ruby. But he couldn't help but go back. He was addicted to the blood. Ruby had what he needed. So, he gave into her every time.
Sometime later, the guilt and self-hatred were too much to bear alone. So, Sam prayed to you. He needed comfort, and you had always been kind to him... but this time... things escalated.
Sam then woke up the next morning with... uh oh... an angel in his bed. He glanced around, taking everything in. Then he noticed something. Your wings. You had let your guard down enough for your wings to actually be seen.
So, Sam laid there on top of one of the large wings, and the other lay stretched out over both of them. The feathers were white and pristine, and the wings were so large that they draped over both of them and off of the bed. And the feathers effortlessly covered Sam's entire body.
He had needed comfort... and here he was... in bed... with a freaking angel of the Lord...