Looking for a replacement for Leonard.
Sheldon had many applicants to be his roommate. In "The 2003 Approximation" knowing that Leonard is truly moving into Penny's apartment, Sheldon starts to interview new roommates. His first candidate is a chemist whom he asks which Chemical element|element on the periodic table is too big for its Breeches|britches. The guy asks if he is joking. Sheldon writes something down as says that there is something else with attitude besides argon. The next candidate is asked if on average he odor|smells better or worse than he does at the present time. The next one is dismissed because he has a Band-Aid on his arm. Up next he describes the candidate as being healthy and in the sciences, though he is running a credit check. Sheldon is on Skype with Amy, who is not going to be his roommate though they eventually move in together. Eleven people have walked out on him. He asks Amy what has happened to him. Sheldon used to be disengaged from his emotions and as happy|happier then. Feelings are a part of life she replies. Sheldon blames Leonard, Penny and Amy with poisoning him with emotions. He's like the Tin Woodman|Tin Man who was given a heart by the The Wizard of Oz (1939 film)|wicked wizard. Amy tells him that he is missing the point of the movie. Then Sheldon realizes he is like Pinocchio made into a real boy due to the wicked Mister Geppetto|Geppetto.
Eventually, after failing to find a roommate, Sheldon resorted to turning his life back to the way it was before he met Leonard in 2003, even going so far as to changing the apartment's layout to its 2003 setting, with everything from before then inside Leonard's room.
He really wanted to have Chris Pratt as a roommate if he was willing to take the smaller bedroom (Leonard's old bedroom). His people never returned Sheldon's messages. Final solution was to have the Hofstadters spend at least half the week sleeping in Apartment 4A, to accommodate for Sheldon not being lonely.
First applicant - the chemist.
Second applicant that doesn't smell right.
Third applicant with the Band aid on his arm.
Amy is not going to be his roommate.