When John Winchester goes missing, he leaves Dean a single message.
"Find Kat Donovan."
She's smart, practical, and a little too happy to be a run-of-the-mill hunter, but offers more knowledge than Dean and Sam have combined. She's young, she's blonde, and she might be a little nuts, but no good hunter comes without their quirks. She's teeming with wit and charm, and knows how to get exactly what she wants. But she's good. Or she tries to be, anyway. And it's about time Dean had something good.