He has a military background, having served in the Bundeswehr, the german army, before retiring out of it after 4 years of service.
He came to chernarus on vacation. Just for fun and for the thrill of trekking the country, alone. When the outbreak hit, he was near Pavlovo. He hid in the woods a long time, trying to stay alive on his own.
He wandered for a long time, looting, scavenging and hunting for his needs. In hindsight it was a good choice to watch all these survival videos and stuff like that in his off-time. It kept him alive afterall. With no hope that his family survived, he's looking for a place to settle down in relative peace.
But to accomplish that he likely still has a long, long long way to go. Afterall, the infected never sleep. So do the bandits and raiders.
Maybe he'll find a group to join, or a group will find him. Or maybe he'll die. The only reason he didn't kill himself yet is because he is certain his family wouldn't want that, if they were still there. And so he keeps fighting for them. To survive, to build a home.
He won't shy away from using violence to serve his own needs.