Gwen Chambers is a cancer patient. She meets Kristina at Kristina's first doctors about discussing the tumor. When she meets Kristina she's in remission. Gwen offers support and love to Kristina in this incredibly tough time and is Kristina's touchstone. The two grow incredibly close and create an unbreakable bond.
Kristina goes to say goodbye to her chemoteam and learns that Gwen's cancer is back.
In season five, episode twenty-one, Kristina recieves a phone call from Gwen's sister telling her that she should go see Gwen, being as she wasn’t doing very well and they knew her time was running out. Kristina visits Gwen and even though she is too weak to respond, Kristina proceeds to tell her about all of her plans and how her life is going. Later in the episode it is revealed that Gwen has passed away. Kristina later gets a package from Gwen that her sister sent following her death that contained an oak tree sapling and a check to help start the school Kristina was planning on building with a card that read, "It's going to be a great school, enjoy the ride! Love Gwen."
Kristina takes it very hard and feels guilty that she survived cancer and Gwen didn't and names the charter school after Gwen to honor her.