Every person has the potential to be unpleasant and harmful, just as every person has the potential to be pleasant and helpful. Think of someone you love dearly; if you look back, you can probably find a time when they did something that harmed you, even unwittingly, or a time when you were angry with them or they were angry with you.
'Enemy,' then, is not a fixed definition, a label permanently affixed to anyone we believe has harmed us. It's a temporary identity we assign people when they don't want what we want or they do something we don't want. But whatever others have or have not done, enemy-making always comes back to us."
Salzberg S, Thurman R. "Love your enemies: Hot to break the anger habit and be a whole lot happier." Hay House, 2013.