Blood
Kreiger asked for a oneshot of Emma going into her parents' room during 2x03 and sees all of the blood on the sheets and Snow lets her know that's where she was born.
After her heart to heart with her mother, Emma made the excuse of exploring the castle to try and buy herself some time to compose herself. She wandered the long, winding hallways and took in the destruction the curse had caused. A cold chill caused goosebumps to rise on Emma's arms with the piles of stone rubble provided little protection from the breezy wind. She came across the room closest to her nursery and wandered inside. It appeared to be a bedroom. A fancy one if the grand four poster bed was anything to go by. She moved nearer to the best to give it a closer inspection. As she did, something caught her eye: the brownish remains of dried in blood. A very large amount of dried in blood. Whatever injury had caused this had not been a small one. Close to the bed where the puddle of dried in blood lay encrusted into the sheet was what Emma suspected was a sword holder, although she'd never seen one before.
Emma could feel another person's presence in the room, and she knew instantly that it was her mother's.
"Is there where he got stabbed?" Emma asked. "You know, carrying me to the wardrobe?"
"No Emma, that wasn't in here." Snow answered, coming and standing beside her. What made you ask that?" Without looking her mom in the eye (Emma didn't want her to see that they were still red around the edges) she pointed at the bloodstain on the bed. "Ah," Snow said. "No, that's not your father's blood; that's mine." Snow answered her. Emma's brow furrowed in confusion.
"Were you injured that night as well?" She asked. Snow smiled gently and shook her head.
"Well, not exactly. That bed is where you were born, Emma." Emma suddenly realised why the sheet was so bloody. She hadn't thought. She had been raised in a world with sterilised hospital beds. "The maid wasn't really in a position to come and get fresh sheets that night." Snow joked, trying to ease the tension. Emma didn't respond.
"That's a lot of blood." Emma croaked eventually, the silence had become too deafening. "I don't think there was that much when I had Henry."
"I didn't really notice is that night." Snow said honestly. "The pain I went through- it all disappeared as soon as I saw you. You were this tiny little miracle. A little person, my little person. "It didn't matter how sore I was. What mattered was you. That you were protected from whatever Regina was planning. Emma, you have to know, if there had been any way for your father and I to keep you…"
"We need to find the others." Emma interrupted her, not ready for any more emotion. She turned her back on her mom and began to leave the room. Snow hung back for a moment, looking at the patch of blood on the bedsheet. It was yet another painful reminder of what had been stolen from her.