Missy's (Raegan Revord) season 5 finale role explains why Sheldon (Jim Parsons) tolerated Penny (Kaley Cuoco) in . The CBS comedy wrapped up its year with an episode that shifts the focus back on its titular character. As Sheldon starts to fear the future, his concerns are eased by his twin sister, re-emphasizing how important their relationship is to his character development.
Since , George (Lance Barber) and Mary (Zoe Perry) have been mostly preoccupied with Georgie's (Montana Jordan) pregnancy situation with Mandy (Emily Osment). This leaves the Cooper twins largely on their own, and while Sheldon looks like he's indifferent to the whole family crisis, it is revealed that his home situation is starting to affect his studies. Ultimately, the constant fighting between his parents and Georgie's new role as an expecting father has caused him to develop a fear of the future. This is exacerbated by the appearance of his first pimple — a biological sign that he is growing up.