Mark checks Theo's profile on Brofinder where he is asking for a date with very specific body proportions. After some deliberation Mark decides to contact Theo and he explains he needs someone to accompany him to his high school reunion party and they have fit the proportions of a tuxedo. He is even willing to pay for a companion. Mark decides to accompany him and Theo arrives at his apartment to pick him up. Once he arrives Penny and Ian intrude on him and Mark, and Penny recognizes him as Theo Matapang, video game developer and tech mogul.
Mark changes into the tuxedo Theo brought for him and they depart for the reunion party. On their way, Theo explains himself further. He says he wants Mark to pretend to be his boyfriend and help him rub on his former classmates' noses who used to bully him how successful he is now. Theo came up with his plan last second after his ex broke up with him one week before the reunion.
The boys arrive at the reunion and are received by Ms McFadden, Theo's horny, improper, former teacher. Theo asks to be seated with Keith, Crystal and Jimbo, the judging committee for the night's titles, such as Least Changed and Most Successful, who Mark and Theo aim to impress. Ms McFadden obliges.
Theo thinks back to his high school times. [Click to expand]
Theo and Mark make their way to table but before they can properly talk Ms McFadden takes Theo on a dance letting Mark do to the talking on his own. Mark can either tell outrageous lies or reasonable ones.
If Mark told unreasonable lies the committee dismisses him and declares Theo the Least Changed. This upsets Theo to the point he rants to the three about how wealthy and successful he is. Mark defuses the situation by pretending to be a stripper and grinding on Theo. If Mark told convincing lies the committee declares the both the Most Changed and Most Successful.
Either way, the boys return to the car after the event ends. Theo admits he was stupid to try and impress, and doesn't actually care about what they think of him. The boys drive to Theo's hotel room and have sex. After it, Theo promises to see Mark again if he is ever in New York City.
Based on his last name, he is likely of Filipino descent.
In the walkthrough, "Date Successful" refers to the ending in which Theo expresses an interest in potentially meeting up again with Oscar in the future; "Game Over" in #23 refers to the ending in which Theo does not express an interest in future meetings after having sex.