Patrick hadn't met Gabe until after his father married Carole Howell after the death of his mother when he was only one-year old. Carole had just lost her own husband as well and his father and the mother of his best friend mourned their losses together before they fell in love themselves, eventually marrying each other and moving into a new house with all of their children.
Because Gabe is a nephew of Carole, Patrick never got into contact with him until he and his family were invited to the Hudbar Manor. He met him, and the two of them never interacted again until Patrick went to Hogwarts in 1991. While Patrick was a first year then, Gabe was a Ravenclaw that just started his second year. They didn't share classes due to them being in different years but they came across each other in the hallways and on the school grounds and occasionally waved to each other as a greeting.
In the summer of 1995 Gabe invited his family and friends to an awesome party that he hosted to celebrate the start of the holidays, and Patrick was invited alongside Brody, Finn and Liam. At first, Patrick didn't really feel like going because he was still sad about his break-up with Theo but after hearing that Theo wouldn't be there and that it would be a great opportunity to have fun and not to think of his ex-boyfriend he still ended up going.
Patrick was incredibly happy that he decided to go to the party and not sulk at home because he has made a couple of new Muggle friends and he enjoyed the music, the drinks and the company of his loved ones. When it was past 2AM, a lot of the people had already gone home, so Gabe saw this as the perfect opportunity to have some alone time with the stepbrother of his cousin. Gabe had heard stories from Brody of what Theo had done and said about becoming a Death Eater and agreeing with Voldemort's cause which was the reason Patrick dumped him in the first place, and so the older Ravenclaw wanted to cheer the sad Hufflepuff up. Gabe was able to make Patrick smile after he cracked a few of his famous jokes before the conversation started to get serious.
Patrick confided in Gabe and told him about his worries and fears of the upcoming First Wizarding War. Gabe started to comfort him and told him not to worry about that at all, especially not at a party, and that they will cross that bridge whenever they get to it. Gabe ordered some more drinks for Patrick and himself and the two of them eventually ended up outside of the venue. Being tipsy from the amount of alcohol both had consumed, they stammered into a deserted, dark alleyway while they kept on laughing and snickering, and eventually they fell against the wall, leaning up against each other. They stared into each other's eyes for a good fifteen seconds before Gabe moved his head and pressed his lips against Patrick's, and the two started to make out. Before it could turn even more intimate, Patrick pulled back and asked what Gabe wanted to do.
Gabe told Patrick that he had only been with girls but that he wanted to experiment with boys too, simply so he could figure out if he was bisexual or not. Patrick then said to him that he was able to be the "experiment" Gabe just talked about and Gabe agreed. Patrick tried to kiss Gabe again but Gabe refused, telling Patrick that they should walk to his house because he doesn't want to have sex with him outside in a dark alleyway where everyone can walk in on them. Besides, it didn't feel entirely safe out there at night, so Patrick obliged and together they walked to his house. only to retreat into Patrick his room where the two of them experimented all night.
Gabe slept over that night. Later that night, when Brody was sitting in the kitchen because he couldn't fall asleep so he grabbed a midnight snack, Gabe walked into the room wearing nothing but his boxer briefs. Not expecting to see his cousin basically half-naked in his house at such an hour, Brody was shocked to say the least and looked at him with a stunned look on his face. When he asked him what he was doing hear, Gabe shushed him because his voice was too loud, and without any shame he told him that he should quiet down or else he'd wake up Patrick, who was sleeping in his own room. Brody immediately knew what had happened between the two and said that he didn't know that Gabe swung both ways, to which Gabe said that he didn't: it was all just an experiment to see if he liked girls and boys, and even though he enjoyed his experiment with Patrick immensely, it didn't do much for him and he'd just stick with girls.
The experiment didn't make the relationship between Patrick and Gabe awkward at all. In fact, it even made it stronger and brought them closer together. Whenever they came across each other on Hogwarts, instead of only greeting each other with a wave, they would stop with whatever they were doing to go to each other and have a little chat. Gabe still hosted more parties to which he invited Patrick to and they started playing Quidditch just for fun. With the exception of themselves, Brody is the only one who knows about their experiment.