It doesn't take long to realize that Stephen's relationship with his mother is extraordinarily fraught. In Episode 5, "Merry F*cking Christmas," audiences instantly get the sense that Stephen's mother must be handled with kid gloves, and all of her children are constantly walking on eggshells so as not to disturb her. Of course, it doesn't work — she's determined to be the victim of every situation she finds herself in.

Neither the show nor the original novel provides an official diagnosis for Stephen's mom, but the book does establish that she has had some struggles with her mental health. In fact, in the book, version of Stephen's mom has been absent from his life since he was a teenager. That's a big change for the show, where Stephen tells Lucy that his mom had to raise him and his siblings by herself after their dad left.