We don't really know who Mr Barnes was just from the title. He could be an ordinary person who found himself in an extraordinary situation. Maybe he was a local businessman, a teacher, or just a regular guy in the neighborhood.
Julian Barnes' novels often have a strong focus on human nature. For example, in 'The Sense of an Ending', we see how the main character's self - perception and understanding of his relationships are deeply intertwined with his sense of self. His works also tend to be very cerebral, making the reader think about complex ideas like truth and memory.
A young WW1 infantryman would make a great main character. He could represent the 'old - school' values and combat style of WW1. When he travels to WW2, he has to adapt to the new warfare, and his journey of adaptation could be very interesting to follow.
One scary story is about the Battle of Stalingrad. The city became a hellish landscape. Soldiers fought in the rubble, and civilians were trapped. There was a constant fear of being shot, bombed, or starving. It was a battle of attrition where the survival rate was extremely low, and the cold added to the horror, freezing the bodies of the fallen.
One idea could be a soldier from WW1 suddenly finding himself in the middle of a WW2 battle. He might use his old - fashioned combat skills in a new and more advanced war setting. For example, his experience with bayonet charges could be a shock to the modern - day soldiers he meets in WW2.
Bucky Barnes is indeed bisexual in specific comic iterations. It's a modern take that brings a fresh perspective to his character and reflects the growing acceptance and inclusion in the comic world.