When Dean is attacked by a Djinn, Sam rescued him and revealed that he had been back from Lucifer's Cage for a year and hunting with the Campbells including their cousins Gwen herself, Christian Campbell, Mark Campbell, Johnny Campbell and long time dead grandfather Samuel Campbell. The Campbells went back to the house Dean was sharing with Lisa and Ben Braeden to catch the Djinn, but when they realize the Djinn are watching the house, Dean suggested they need to leave, and the Djinn attack.
Gwen was at the compound with Samuel, Mark, and Christian when Dean and Sam arrived with the baby Shapeshifter. According to Samuel, Christian and his wife, Arlene, had been trying for a baby. Christian agreed to take in and raise the baby Shapeshifter, but when the Alpha Shapeshifter appeared, he overpowered them killing Mark in the process, and took the baby back.
When the Campbells went after the Alpha Vampire, Samuel ordered Gwen to stay back with Dean and "sweep any stragglers" they flush out. She noted that Samuel often tries to keep her out of harm's way, possibly because she reminded him of his daughter, Mary Winchester. They fight well together, but Dean refused to take her hand up when she decapitates a vampire that took him down. He then left her alone to investigate what the others were doing with the Alpha Vampire, but she still covers for the fact that he snuck off. Later she sided with Samuel against the Winchesters, holding them at gunpoint and forcing them to disarm when they were discovered talking to the imprisoned Alpha Vampire. Also, when it was revealed that Samuel has been working with Crowley, she still followed his orders and left with him.In ...And Then There Were None, Gwen was hunting with Samuel, investigating deaths related to a spike in the activity of supernatural creatures. While investigating the murders, they ran into Bobby Singer, Rufus Turner, Sam, and Dean Winchester at a cannery. Gwen told Dean that she didn't know about Samuel betraying Sam and Dean to Crowley in Caged Heat. While they were alone, the creature responsible for the deaths, the Khan worm infected Dean and used him to kill Gwen.