Why was Paul so fond of Kat? Would they have had the same relationship at peace time?

When Paul gets to the army, he is a scared boy. He doesn't know anything about camp and certainly knows even less about fighting. Kat takes him under his wing. There is a father son thing going on here as well as brotherhood and camaraderie. Kat keeps Paul alive from bombs, gas, and bullets. He also keeps Paul fed and helps him through his despair. No, I don't believe they would be friends in peacetime. Paul would be living the life of a young man, chasing girls and going to school. Paul would not likely be hanging out with a man old enough to be his father.