I read an English adult book about around three to four years ago (it seemed quite fresh at the time) which was about a seventeen-year-old boy in the early 20th century, who was shot and became immortal after seventeen minutes underwater, albeit functionally dead. He has certain relations with a film star in the twenties which causes him to lose functionality in certain areas.
The book has a sequel as well, which I remember entails him taking a job from NASA on the Hermes spaceship as he can't die. He is also attacked by chainsaws in the sixties from enemies he made decades earlier and loses an arm.
The front cover had a steampunk-esque aesthetic though, with sun rays and the like. Both books were hardbacks, relatively thick (maybe about a thumb's length). I ordered them from a library. Any idea what these books could be?