What specific behavior deepens friendship?

You've answered your own question, I think. If you want to be trusted, you must be trustworthy and behave in ways that earn that trust from your friend (and vice versa). Being open and honest with them, doing what you say you'll do instead of making excuses, and putting your friend's desires ahead of your own are a few good ways to deepen a friendship.To know that you would do anything in your power to protect your friend, and that he/she would do anything to protect you, is the truest sign of friendship.

"Greater love hath no man that this, than a man lay down his life for his friends. " John 15:13.

Giving. Like true love friendship is NOT a game of give and take, but rather a game of give and give. The more you give to anything the more you love it (babies, puppies, work).

So give 100% and the friendship will deepen.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.