It's never easy to be nice to someone who always seems to rub you the wrong way. If you have someone in your life who brings out the worst in you, it can challenge some of your core values about who you are and how you treat others. Learn to fight your most uncharitable tendencies by reminding yourself of what it means to you and by examining the core reasons why this person is stirring up such negative feelings.
Set some rules for yourself in terms of your own personal standards for behavior towards others. Understand that at this stage, it's about you, not them. Use statements like, “No matter how much I dislike someone, I would never...” and make a list of things you would never allow yourself to say to or do to anyone. Make positive statements, as well, as such, “Even with someone I hate, I will always...” Make some rules broad and some specific. Think about your own tendencies and your own worst temptations in terms of mean or immature behavior and guard specifically against those.
Write the statements you've made and keep the list somewhere where you will see it every day. Consider these statements to be promises to yourself.
Think about the specific reasons why someone rubs you the wrong way. Understand that you can learn a lot about yourself by examining these things. Chances are, you dislike the person because he reminds you of someone who's caused problems for you in the past, or because he displays traits and characteristics that you find particularly unlikable.
Examine yourself in terms of your dislike. Ask yourself if those objectionable behaviors are things that you are afraid of in yourself or that you are particularly hard on yourself for displaying or are afraid you might display. You may find that going easier on yourself about some key issues may make it easier to be kind to this person who irks you.
Try to develop some empathy for the person. Imagine what it's like to be him. Imagine his life and experiences in the richest, most complete detail you can. Think about the ways in which his life is different from yours and the different influences that have affected you both. With his worst behaviors, think about ways in which emotional pain may be influencing him, or consider that he might never have been taught a better way to behave and what this means about other areas in which his life has been lacking necessary social learning.
Think of ways you can take an assertive stand against the worst of the person's behaviors, especially if you believe the actions and attitudes to be truly cruel, unfair or unjust. Bear in mind that your dislike may be because of your own feelings of helplessness, but you may be able to curb that by being firm. Make a few “I” or "we" statements to him about how his behavior is affecting you and others negatively. This might be something like, "I need feedback that's more constructive and positive," "I find it difficult to respond well to being spoken to that way," or "We need to keep complaints to a minimum and direct them to the proper channels, please." Do this at key moments and pick your battles. Look for times when the message is likely to be heard.