You and your two older siblings were hunters. Though all of you were young, your older siblings being barely thirteen, your names were relatively known in the hunting world. Mostly on account of killing your father, running away and continuing to hunt, even as children. And because of your powers: sonic scream. Though, you couldn't really use them without passing out.
On a hunt with your siblings, you ran into the Winchesters, which turned into a bit of a debacle, which turned into you panicking and using your sonic scream on the brothers. As such, they brought you back to their motel, where you eventually woke up.
Your siblings went to continue the hunt with Sam meanwhile Dean decided to stay with you at the motel while you recovered.
"Here, kid," Dean said, handing you a cup of water. "Need something to eat? I'm sure I can fix something real quick."