AN: Hi! I'm not new to Supernatural as a TV show, but this is my first story in this fandom! I hope it's not too bad or off and that anyone who reads this enjoys it!
From the very beginning, Sam and Dean had had a nearly unexplainable bond. It wasn't just that they were brothers; they were so much more than that. They were support for one another. Dean was often Sam's only support for anything he did. He was Sam's mother, and father most of the time too. Sam was the one Dean was able to open up to, even though he didn't do it that often.
So it should be no surprise that one night, after being up at all hours with a nearly one-year-old Sammy who was teething at the time, Dean did not react when Sam turned his head on his shoulder with his tiny thumb in his mouth and his eyelids drooping and mumbled, "Dada," as he fell asleep.
Dean may not have reacted but he did think it was a fluke, so he just whispered, "G'night, Sammy," to the now sleeping baby as he gently put him in the borrowed crib the motel's owner had dug up from her basement after seeing how tiny and cute Sammy was. Usually Dean just slept with Sammy beside him in one of the two beds in a room, but he had begrugingly watched their father accept the crib hesitantly. Dean had made sure the crib was just inches from his bed though.
He gave no more thought to the incident that night. Until it happened again weeks later as he was feeding Sammy his breakfast of a cut up banana or two. With Sammy sitting in his lap as he sat in a chair at the small table in their current motel room, Dean would carefully cut a slice of banana from the fruit that lay on the dinged-up table with a plastic knife, which was all they could afford in the way of silverware; It was plastic utensils or nothing at all- and then hand them to Sammy so the boy could feed himself. Except Dean had spaced out for a minute while thinking about where their dad had gone off to a little more than a week ago, and had not cut any more pieces in his daze, and so Sammy became frustrated and had to make his displeasure known, as all babies did.
With a grunt, he ordered, "Mor' 'nanan, Dada!" rather loudly, shocking Dean out of his daze.
His first reaction was to wake up from his daze and scold Sammy, and he did this with a quick, "No screaming, Sammy!" And then as Sammy's chin began to wobble from being scolded, Dean registered what his baby brother had just said. He cocked his head in confusion as he tried to process it. And then Sammy's waterworks began with a cry of, "Dada!"
Dean's confusion gave way to his big brother mode and he stood up from the chair by the table, puttting Sammy on his shoulder as he shushed him.
"Shh, it's okay, Sammy Boy. You just scared Dada." Dean paused. He had meant to say, "You just scared me," but the word had just slipped out. Dean was shocked to realize how natural it felt to say it in relation to himself. After thinking it over for a moment, Dean made a decision, "Okay, Sammy, you can all me Dada, but only when we're alone, you got that, Kiddo?"
Dean knew that Sammy's gurgles of content now that Dean had resumed feeding him were a sign of understanding from his baby brother.