Proverbs 25:21-22
If your enemy is hungry, give him bread to eat;
And if he is thirsty, give him water to drink;
For so you will heap coals of fire on his head,
And the Lord will reward you.

Think about how an enemy comes about.
In my opinion, pride and greed are the two leading causes of making enemies.
Pride does not let someone apologize or seek a peaceful resolution to a conflict.
Greed leads to taking more than you need or doing anything to acquire what does not belong to you.
Despots and dictators are the perfect examples of pride, greed, and enemies.

This verse hung around for years with little impact on people. By the time of Jesus, it was all but forgotten and those people that mistreated or complained against their enemies found themselves getting a lesson.
“Love your enemies, bless those who curse you, do good to those who hate you, and pray for those who spitefully use you and persecute you, that you may be sons of your Father in heaven; for He makes His sun rise on the evil and on the good, and sends rain on the just and on the unjust. For if you love those who love you, what reward have you? Do not even the tax collectors do the same? And if you greet your brethren only, what do you do more than others? Do not even the tax collectors do so? Therefore you shall be perfect, just as your Father in heaven is perfect.” Matt 5:44-48

Paul quoted the wisdom of this proverb and added, “Do not be overcome by evil, but overcome evil with good.” Rom 12:21

Do not let enemies define you. Define yourself before them. Your godly attitude has the ability to change an enemy into a friend.