Sam W and Dean W

Sam and Dean were about to leave their motel, heading towards another hunt...

When they were about to leave, there you were. In a basket in front of the motel door, with a letter.

As soon as Sam and Dean noticed you, they were completely confused, the letter said that you were Dean's daughter, and that you were in his care.

Now you were both back at the motel, Dean reading the letter over and over pacing the room while Sam had you on his lap, you weren't more than a year old.