Research Assistant (Physics)
Toby Loobenfeld is a in the Caltech lab with a double major in theater and physics (since his " parents" pushed him towards the latter) from MIT, who is cast by Sheldon to play his nonexistent drug addicted first cousin "Leopold". Toby regards Sheldon's motivation for Leo's substance abuse problem as pop and plays the role as if Leo was abused in the by a club-footed when he was fourteen years old. Sheldon becomes disappointed with Toby's portrayal and acting abilities, exclaiming that his parents did the right thing in pushing him towards physics. Later, Toby takes advantage of Penny's comforting attitude toward Leo to snuggle and bond with her, much to the chagrin of Leonard and shared surprise of Sheldon.
Leopold "Leo" HoustonEdit
Leopold is a construct Sheldon creates as part of an exquisitely convoluted, "un-unravelable" web designed to replace a ruse concocted by Leonard that Sheldon deems laughably transparent. After Leonard deceitfully told Penny that he couldn't come to her performance in a one night showcase production of ' because Sheldon and him were attending a on molecular given by Dr. Emil Farman-Farmaian, Sheldon conceives a new lie in which he tells Penny that Leonard was untruthful because he wants to protect Sheldon from the embarrassment of having a drug addled cousin "Leopold" and that they are actually going to participate in Leopold’s in to convince him to return to rehab.
Believing the success or failure of their deceitful enterprise turns on details, Sheldon creates for Leo a Facebook page, an online blog depicting his descent into drug use, and a desperate yet hopeful listing on . According to the character profile Sheldon wrote for him, Leopold Houston is 26 years old and originally from , but was a , so he was brought up on a variety of military bases around the world - as a result he's often felt like an outsider, never really fitting in, which is probably the reason for his substance abuse problem. As the quintessential middle child, Leo's addiction is meant by Sheldon to be rooted in his unmet need for attention, along with a genetic predisposition to inadequate serotonin production.