One way could be through his diplomatic skills. Harry might be able to negotiate with the goblins in a very fair and respectful way. He could understand their concerns and offer solutions that benefit both parties. This would make the goblins see him as an intelligent and reliable person.
It could be about a boy with some extraordinary physical feature (big penis being a very odd and inappropriate way to describe in a normal context here) doing something amazing at the beach like rescuing a drowning person, which impresses everyone there.
One common scenario is at Hogwarts. Maybe during a school project or competition, Harry's unique approach and determination lead to success, and Zabini, being a spectator, is impressed. For instance, in a Potions competition, Harry might come up with a brilliant solution to a difficult potion - making problem.
In this fanfiction, Gohan might learn valuable life lessons from Grandpa Gohan. Maybe Grandpa Gohan would teach Gohan some old - fashioned martial arts techniques that have been forgotten over time.
In such a fanfiction, perhaps future Gohan could warn present - day Gohan about upcoming threats that he has faced in his own timeline. He might share his experiences and knowledge, which could make present Gohan a stronger fighter and a wiser person.
Piccolo might also be a savior. He has a soft spot for Gohan since they trained together. He could use his strategic mind and powerful attacks to outwit Raditz and rescue Gohan. Maybe he teams up with Goku for an even more epic rescue mission.
Perhaps Gohan's own overconfidence could lead to his death. He might underestimate an enemy's power or a dangerous situation and make a wrong move that results in his end. For example, he could rush into a fight without proper preparation thinking he can handle it easily.
A possible plot twist could be that future Gohan is actually an impostor sent by an enemy to manipulate the real Gohan. Another twist might be that when they meet, their powers combine in an unexpected way that causes some sort of time rift or a change in the timeline.