Mercy is compassion or forgiveness to a person who did something wrong or that you are in the position to punish.
Kindness is being friendly, generous, considerate. It is thinking of someone higher than yourself and going out of your way to do something.
You should always be kind, it is important to be kind. Often people remember that you were kind even more than what you said or did. Kindness and Mercy is admired. You should also always be merciful, but you must know that if someone does something wrong constantly mercy can't always be the answer. However, people should be kind and merciful all the time.
