The most important book to read for pagan morality is Havamal. It is reciprocal morality. In Havamal it states

Return a gift for a gift but repay evil with evil.

The idea of gift for gift is multi-sided. A gift can be a kind word. But gift giving has multiple functions, it serves to create alliances among people to facilitate cooperation which is power.

Giving a gift for a gift encourages people to help you in the future. Repay good for good. The purpose of repaying evil for evil, such as saying something mean to someone who was unkind to you, or praying against someone who was unkind, the purpose of this is to let Nature know that being abusive towards you comes with a price, this makes creatures less likely to try to prey on you.