I can't believe that with that kind of past, you can ever return to 'being a nice bloke'. Sounds like a facade and fundamental lack of integrity. But I clearly don't know the individual in question.
Or perhaps it was a case that he would do whatever was necessary to get whatever he wanted?
Once he had it, he could return to type.
I suppose the best analogy in comparison of that is a couple of my mates Grandad. As a teenager he was so sensible and cautious, he got the nickname Gramps which stuck with him all his life.
When we went to Portugal years ago for the 'Gramps' golf tournament (24 of us went) and one of Gramps school mates went with us. 22, 20 something **** heads, and two 80 year olds.
Anyway, one night in a bar I was chatting with Gramps school mate and asked what was he like during the war (they were both there on D-Day).
He said you have never seen a change in someone as he had with Gramps in uniform. He went from a quiet, cautious, sensible young man to an absolute fearless 'animal' who would do whatever it took.
Gramps came back with numerous medals for gallantry, whereas his mate came back with campaign medals. He said he wanted to do his bit and come back in one piece.
Gramps wanted to get whatever they were doing done. And he would be the man to lead from the front. Totally the opposite of him out of uniform.
When the war finished, Gramps went back to being the quiet, sensible, cautious one.
That golf trip was the first any of his grandsons had ever heard a single story about his war exploits. Never knew about his medals, never even knew he was at D-Day, nothing.
Some of the greatest stories I've ever heard were on that golf trip, by two old boys who "were there" shame he never wrote a book.
He never said anything about them, as in his words "didn't think anyone would be interested in them".
A remarkable fella. The likes of which it's unlikely we'll ever see again.