Jack had been born and seemingly been a grown man in seconds after birth. You, his twin, on the other hand, chose to stay a baby. Jack knocked the Winchesters out with some nephilim power and when they woke up, they woke up to you wailing.

Sam swore under his breath, quickly picking you up, quickly realizing Jack was missing.

"Shhh, it's okay," Sam tried to soothe, looking at Dean as he stood up.