Her father goes missing for five days without checking in with her, so Krissy calls Bobby Singer, but another man answers the phone. She is eventually visited by Sam, who offers to find her dad for her. While Sam visits, Krissy pretends to not know that her father is a hunter. Sam attempts to keep the truth from her by asking her for coffee. Before Sam leaves, he gives her a number to call if he doesn't come back.
When Sam doesn't return, Krissy calls Dean, who comes to her place. When Dean reaches Lee's closet, he realizes the map was torn out and Krissy reveals that she knows her father is a hunter. Lee had told her to pretend to be an ordinary kid in order to hide, and she used this on Sam. Krissy tells Dean that every time someone sees this and goes looking, they don't come back. She also demands Dean takes her with him. Dean tells her no, but Krissy reveals that she burned everything but knows the location forcing Dean to take her along.
In the car, Dean is in no mood to talk, but Krissy asks him how he knows things about the Vetala that Sam and Lee didn't. Dean reveals he hunted a pair when Sam was at Stanford. Krissy is surprised that Sam went to college, and Dean suggests she could too.
At the truck stop, they watch Sally take a trucker into his truck - and then Krissy notices Marlene getting in the cab and driving it away. They follow it, and then Dean cuffs her to the steering wheel and takes the precaution of confiscating her lock-pick. However, she manages to pick the lock with a bobby pin.
Dean enters the building where Sam and Lee are being held, and he knocks down Marlene, but Sally manages to grab Krissy who has followed Dean. However, Krissy manages to stab and kill Sally with a silver knife. Krissy frees Sam and hands him her knife which he uses to kill Marlene.
Sam and Dean visit Lee in the hospital and advise him to get out of hunting. Lee protests that he got into it for his family and Dean says he should get out for the same reason. Later, Krissy tells Dean that they are leaving the life.
Krissy is now older and more mature than she should be for her age. She lived with Victor Rogers who was kind of a mentor after her dad was killed by a vampire, along with Josephine and Aidan. All three kids lost their families to vampires and Victor used to provide them opportunities for revenge.
However, it was revealed that Victor and a vampire were in league with each other and were training the kids to be better and faster hunters than those of the previous generations. The vampires they kill aren't the actual killers of their families. They were murdered on the orders of Victor himself so that the kids could be motivated to take up hunting.
Krissy at one point did have Victor at gunpoint but upon Dean's words, became the bigger person and let Victor live, who immediately committed suicide.
She said that she would try to live a normal life and not go looking for trouble, but wouldn't back down if trouble came looking for her.