Mary thought she was prepared, but seeing Sam in person, hearing the polite voice as he extended his hand and spoke those words took her breath away. There was, in Mary's opinion, something inherently wrong with children calling their parents by their first names. Even if Sam was locked inside himself and meant her no real disrespect, some part of Mary cringed at hearing him ask that.
And then there was the part of her that was aching from the force she was having to use to restrain herself. She wanted to pull him close, to tell him that his mother was THERE and that she would fix it all and nothing could ever hurt him ever again, but she knew it was a bad idea. More than that, it wouldn't work. Though she felt she might shatter at the seams in the blink of an eye at the force of will she was using on herself, Mary swallowed hard and extended her hand.
"Mary Winchester." Your mother, she added silently. "I want you to look through all of this. Keep in mind we were only pulled to LA a year or so ago, so there's very little in the way of childhood photos, but I think you'll see that you are very happy, and one of us as well."
And as she let go of his hand and took a step backward, Mary prayed for just that.