When Tam reaches out to Sheldon after 20 years because he is visiting Caltech with his son, Sheldon is visibly upset. He reveals that Tam has been on his for decades.
: Tam stayed in Texas after meeting a girl, leaving Sheldon to move to California alone. [S12E4] The Tam Turbulence
While the guys deal with Tam, Penny and Bernadette take Raj's fiancée, , out for dinner. "The Big Bang Theory" The Tam Turbulence (TV Episode 2018) When Tam reaches out to Sheldon after 20
: The episode highlights how much Sheldon has grown and the value of his current "found family". Subplot: Meeting Anu Penny and Bernadette take Raj's fiancée