In "30 Years of Science Down the Tubes", Phil says goodbye to Carol as he drives off in a DeLorean to his childhood home in Tucson, believing Mike may be there. After arriving and entering his childhood home, his theory is correct that Mike is there, however, he finds Mike in an un-moving state. However, Mike springs up and scares Phil, as he reveals it was to prank him. Later that day, Mike and Phil go through some old memorabilia. They begin to dig through the box where Phil finds an old experiment of his where he farted into a jar to open thirty years in the future. Mike tries to explain to him that the fart has dissolved, however, Phil desperately believes that it's still there. As he opens the jar, Mike silently farts, much to Phil's anger that Mike ruined his experiment.
To get back at him, Phil pretends to catch Mike's sickness by putting hot sauce into his hand. As Phil continues to joke around, Mike tells him to stop with the pranks, but it leads to Mike admitting Phil takes nothing seriously. As Mike tells him to be honest, Phil tells him he dislikes his haircut. Feeling bad about it, Mike cuts his hair and gives him a new look, much to his happiness. When he eventually finishes, Mike tells him to leave, but his joking turns into him lashing out at Phil about how his life has been a mess and a joke.
With Phil upset, Mike goes out to apologize to him and the two patch things up. Heading inside, Mike notices his parents' graves, learning that Phil had to bury them. Feeling bad that he had to bury them, and a tombstone for himself believing that he had died, Mike requests as his "dying wish" to go back to Malibu. As they part ways, Mike gives him a new fart jar to open in another thirty years. After hugging it out, Phil decides to give him his sports ball collection since "they" helped him when he was alone. The two part ways with Mike staying in Tucson and Phil heading back to Malibu.
In "The Open-Ended Nature of Unwitnessed Deaths", after leaving a note for his potentially deceased boyfriend, Mark, Lewis says that Phil at least got to see his own brother pass, leading Phil to question Mike's fate. He goes to Tucson to the Miller House. Entering the house, he views photographs of Mike's heroic accomplishments and some of his more ridiculous ones. As he heads to Mike's door, he cannot come to terms that his dead brother's body may be in there, and decides to leave a note for him as well. He notices his sports balls and takes Gary with him. Lewis and Phil then return to San Jose, California to the office building.