Want to buy a book for bf but not sure what to get him!

I wanted to buy my bf a book recently but a majority of our interests don’t align, so I’m a bit unsure of what to get him. He likes history, knows a lot about wars, enjoys Eastern European history specifically. I believe he enjoys sci fi but that may be limited to movies and I know he enjoys philosophy but I don’t want to get him a very lengthy wordy philosophy book that feels like a drag to read at the beginning. Fiction or non fiction work, maybe something like notes from the underground? please help haha