In "The Pulled Groin Extrapolation", he is one half of the Department of Primatology's Brangelina. When Amy Farrah Fowler needed a "plus-one" to attend the wedding of Doctor Morelli and Doctor Gustafson, Sheldon preferred to attend a model railway show instead. Undaunted, Amy asked Leonard Hofstadter, since the last time she took Sheldon to a wedding, he complained the whole evening. Leonard reluctantly escorted her, but they bonded over comparing notes about their respective appalling mothers. Sheldon was moved to an expression of uncharacteristic jealousy on realizing how well they bonded, but Amy confided to Penny that "Leonard just doesn't get my motor running".