Not even five days later, the doctor comes in to tell his mother that it took a while, but her body is getting better. Stiles pretends like he doesn't understand while his mother and father – a bit weird to think of them like that now that he's had his little revelation – nod along and agree with the doctor. His mother insists that she doesn't need the chemo anymore, despite the doctors' recommendations and his fathers' protests.
In the end she wins – she always does – and five days later they leave the hospital behind. The doctors can't explain it, but her illness has dissipated. His father noticed, though, and on the car ride home he suggests that she call up Talia and invite her to dinner. Stiles adamantly agrees – because he has more knowledge than his father on this subject – and Claudia concedes that she would enjoy seeing more of Talia.
So for the next few months Claudia spends her weekends up at the Hale house. She visits the doctors' once a month and they still cannot explain where her cancer went. She teaches Stiles how to cook and how to use his Fay powers, even though he'd gotten a pretty good grasp on that on his own. He's rather happy with his life in general.
But Scott can be rather bright when it comes to certain things. Stiles acting weird is one of those things. One day, Scott and Stiles are sitting outside their school waiting for Claudia to come pick them up when Scott brings up Stiles' behavior.
And Stiles can't lie to that face, not even after all his years of trying. So he tells Scott about the other universe, the one he's actually from, without all of the gruesome details. He tells Scott about werewolves and fay – and he has to secretly show Scott his powers which has Scotts eyes nearly popping out of his head – and about how he was one. He tells Scott all about their pack and about Derek and the spell. He tells him about all of the fears he'd had, all of his thoughts about everything, and even his suspicions that Derek tricked him into getting himself to safety but he has no way to prove it.
When his mother pulls up, Stiles just walks to the car with Scott in tow. Scott is surprised to find out that Claudia is fay as well, but he takes it in stride. He asks questions Stiles hadn't thought of and his mother answers all of them with a smile on her face. Later that night after Scotts gone home and the leftovers have been put in the fridge, Stiles asks his mom if she's upset that he told Scott.
She tells him that she wouldn't have expected him to lie, but he should know that he can't tell everyone about their kind. That's when Stiles realizes that he never told his mother all of the details about his other life. So he tells her that Scott was a werewolf in his universe and he trusted Scott with everything he was and could ever hope to be. That night, while John's working a double shift, they stay up and Stiles tells his mother about his other life and everything it entails. He keeps out a few facts, like the Hale house fire, and that Derek was the Alpha of their rag tag little group. He does end up telling her about their deaths though. Something he never got around to telling Scott.
She just holds him and tells him how strong he is and how proud she is to be able to call him her son.