I'm not sure specifically as I haven't read it. But generally, it might be about a kid who is the last one in a certain situation, like the last one remaining in a competition, or the last one surviving in a dangerous place.
The last bullet left for me is usually found in science fiction or horror novels. It's about a character who is hit by a bullet in the last battle and is on the verge of death, but he still struggles resolutely to complete his mission or pursue his goal in the limited time. This plot was often used to emphasize the fragility and shortness of life, as well as the choices and decisions humans made in extreme situations.
It's purely fictional. The movie was created based on a script, not real events. The creators came up with the plot and characters to scare and entertain the audience.
I'm not entirely sure as I haven't read it specifically. But generally, it might be related to the topics that the 'Last Podcast on the Left' usually covers, like true crime, horror, or the supernatural, presented in a graphic novel format.