I wanted everybody to stay the same, but they just didn't.
He is shown wearing an olive-colored pilot's jacket and a gray undershirt along with khakis and black boots. He also wears a brown aviator hat which covers his silver hair. His wrinkled face and lighter skin differentiates him from his cousin Greg Universe, although the two share similar noses.
Andy is a traditionalist, initially shown to be stubborn, judgmental, hot-tempered, and willing to hold a grudge. He is guarded and cautious in his attitude to the Gems, dismissing them as "hippies" because of their unusual appearance and lifestyle, and resistant to social change and deviations from the status quo in general. As he settles down and gets accustomed to the recent changes, however, he displays a lighter side, happily talking to Steven about his life as a pilot and ultimately allowing Lapis and Peridot to stay in his barn. Towards the end of his debut, he reveals that he is bitter due to the changes in his life, primarily of the distance that grew between himself and his family and shows regret of not changing before meeting Steven.
Andy flies to his parents' barn and is upset to discover it has been remodeled. He is immediately met by Peridot, Lapis, and Steven. After concluding that they are homeless hippies, Andy furiously demands they vacate his property. Unsure of how to handle the situation, Steven contacts Greg, who arrives after some time with the other Crystal Gems. To the Gems' surprise, Greg introduces Andy as his cousin. Andy is similarly astonished when he discovers that Steven is Greg's son, but cheerfully greets his first cousin once removed. His mood takes a turn for the worse, however, upon learning of Greg's decision to change his surname to "Universe". He finds his cousin's association with the Gems likewise troubling, now regarding the magical beings as illegal immigrants after Greg refers to them as "aliens". He eventually restates his demand for Peridot and Lapis to leave, having established that the Barn is for the DeMayo family. Steven proceeds to persuade Andy to have a meal with the Gems, hoping that he would come to consider them as family and allow them to stay. Relations appear to initially worsen throughout preparations, however, as Andy continues to find the Gems somewhat unusual and becomes angry at their disassembly of his parents' plane. Nevertheless, Andy slowly warms up to everyone. He speaks fondly of his past experiences to Steven and Greg, and is later amused by the Gems' attempt to please him with various objects related to the human celebrations of marriage, birth, and death. When preparations are completed, the group sits down to dinner outside the Barn. As the meal progresses, Andy begins to feel out of place among the others, prompting him to abruptly cede ownership of the Barn before flying away in his plane. When Lapis and Steven catch up, Andy expresses to Steven his bitterness regarding his futile efforts to resist the changes his family experienced. Steven responds by explaining his desire to learn more about his human relatives, after which Andy comes to realize that he could have adjusted to the changes in his life and stayed in touch with the members of his family. Steven assures him that it is not too late to do so, and the two fly back to the Barn where they are met by the Gems and Greg, all of whom are glad to see their return.
Andy takes Steven and Greg to Korea in his plane.
Steven was shocked to find out he had a relative he previously had no knowledge about, but immediately tried his best to befriend Andy despite his dismissal of Greg and the Gems. After agreeing to have a family dinner with Greg, Steven, and the Gems and finding his prejudices being challenged, Andy left the barn to Lapis and Peridot and took off in his airplane. When seeing this, Steven followed him in the air hanging from Lapis' arms and shouted out to him to talk him out of leaving. Steven explained that even though the Gems are his family, he needs contact with his human relatives as well, and was happy about getting a new member. Having grown attached to Steven, Andy saved him in his airplane from falling from a great height, and they agreed to stay in touch with each other.
Greg is Andy's cousin who used to come the family barn based on tradition. After Andy's debut into the modern timeline, the amount of things that changed and how Greg contributed to it led to some bitterness towards each other. It would eventually be resolved at the end of the episode.
Andy's relationship with the Gems starts off poorly. Upon meeting them in "Gem Harvest", he is infuriated with Peridot and Lapis for their modifications to the barn. He assumes them to be homeless hippies, and angrily demands that they leave his property. Andy is further upset when Greg informs him that the Gems are "aliens", interpreting this as illegal immigrants. At first the Gems reciprocate Andy's mistrust. However, wanting to maintain possession of the barn and good relations with Steven's family, they decide to make an effort to understand and befriend him. Despite their initial wariness, Andy and the Gems gradually warm up to each other over the course of the episode. The Gems are thankful for Andy for bringing them together, and he has seemingly come to accept the Gems as family, allowing them to stay at the barn.
|1. "Kindergarten Kid":||Absent||14. "The Zoo":||Absent|
|2. "Know Your Fusion":||Absent||15. "That Will Be All":||Absent|
|3. "Buddy's Book":||Absent||16. "The New Crystal Gems":||Absent|
|4. "Mindful Education":||Absent||17. "Storm in the Room":||Absent|
|5. "Future Boy Zoltron":||Absent||18. "Rocknaldo":||Absent|
|6. "Last One Out of Beach City":||Absent||19. "Tiger Philanthropist":||Absent|
|7. "Onion Gang":||Absent||20. "Room for Ruby":||Absent|
|8/9. "Gem Harvest":||Debut||21. Lion 4: Alternate Ending":||Absent|
|10. "Three Gems and a Baby":||Absent||22. "Doug Out":||Absent|
|11. "Steven's Dream":||Appears||23. "The Good Lars":||Absent|
|12. "Adventures in Light Distortion":||Absent||24. "Are You My Dad?":||Absent|
|13. "Gem Heist":||Absent||25. "I Am My Mom":||Absent|
|1. "Stuck Together":||Absent||13. "Your Mother and Mine":||Absent|
|2. "The Trial":||Absent||14. "The Big Show":||Absent|
|3. "Off Colors":||Absent||15. "Pool Hopping":||Absent|
|4. "Lars' Head":||Absent||16. "Letters to Lars":||Absent|
|5. "Dewey Wins":||Absent||17. "Can't Go Back":||Absent|
|6. "Gemcation":||Absent||18. "A Single Pale Rose":||Absent|
|7. "Raising the Barn":||Absent||19. "Now We're Only Falling Apart":||Absent|
|8. "Back to the Kindergarten":||Absent||20. "What's Your Problem?":||Absent|
|9. "Sadie Killer":||Absent||21. "The Question":||Absent|
|10. "Kevin Party":||Absent||22. "Made of Honor":||Absent|
|11. "Lars of the Stars":||Absent||23/24. "Reunited":||Non-speaking|
|12. "Jungle Moon":||Absent||25. "Legs From Here to Homeworld":||Absent|
- The name "DeMayo" is a spelling variation of "Di Maio", a surname found in Sicily and southern Italy.
- The name "DeMayo" is also found among Sephardic Jewish families from Spain and Portugal.
- Andy's personality and conservative political views are based on common right-wing stereotypes.
- His mannerisms are also very similar to the character Carl from the show Aqua Teen Hunger Force who is voiced by the same voice actor. The most notable difference is Carl being a lot more foul-mouthed and nasty due to the adult nature of ATHF, as well as dressing more slovenly.
- Andy's surname, DeMayo, is similar to Nick Demayo's, an animation director for "Gem Harvest" as well as the series in general.
- Andy asks Steven to refer to him as "Uncle Andy" despite them being first cousins once removed. In certain cultures, referring to a distant relative as an aunt or uncle is seen as a sign of respect, while in others, it is a sign of affection.