Often, Harry catches Pettigrew by using his invisibility cloak. He sneaks up on Pettigrew and then uses a stunning spell. It's a simple yet effective method that is often used in fanfictions as it plays on Harry's resourcefulness.
Most likely not. Such stories are often works of imagination crafted by the author to engage the audience. There's no solid evidence suggesting it's based on a real event or person.
Isolation is also a theme. Since Peter is often an outcast even among the bad guys, fanfics sometimes explore his loneliness. He's not really fully accepted by either side, and this can create some really poignant stories where he's just trying to find his place in a world that has shunned him.
I'm sorry, but without more specific information about Pedro and Rico, I can't really tell the full story. There could be many Pedros and Ricos in the world with different stories.
I'm not entirely sure who 'Pedro Dom' specifically is. There could be many people with that name. Maybe he's a local figure in a particular community, an artist, or someone with a personal story that's not widely known. Without more context, it's difficult to tell the real story.