We don't get to know a lot about Sven the character in the novels. He is supposedly an Auslandeutscher of Danish-Austrian descent. He gets shell-shock every now and then and is generally portrayed as the weakest of the veterans in the section and also the youngest.... But he's the best grenade thrower (110 metres) and best machine gunner (Liquidate Paris Chapter 7).|
He does insist on mentioning his sexual ability at every opportunity and all his girlfriends are left in a state of bliss once he's tried out his oriental skills on them (it says here). In Legion Of The Damned he marries Ursula who is later killed (typical) in Chapter 22 'Death Rolls Up'.
In Legion Of The Damned Chapter 1 'Filthy Deserter' Sven is referred to as "Sven Hassel, Gefreiter in the 11th Regiment of Hussars".
In Monte Cassino Chapter 11 there's a bit where Sven is crawling through no-man's-land to the American trenches and he's watching an American he has to kill and he hears the guy being called "Bob" and he says 'Strange that I have to kill a man with my own name - Bob kills Bob' Which is a weird comment. (Erik Haaest's biography refers to Hassel as Bob de l'Arbin, but also says that this is a false name. And why would he suddenly refer to his "real" name when he always uses "Sven" in the books. Very odd. Can't explain that one!)