As nice as you may be, you can't be sure your coworkers will be as pleasant. At least one time in our lives, we've all had a coworker who just grates on everyone's nerves or simply has to be the troublemaker or gossiper. Don't worry, though; there are methods you can employ to deal with any less than desirable coworkers.
Try to understand what is causing your coworker to be difficult or combative. Sometimes, stress at home or at work can negatively impact how an individual will perform at work. This can then translate to an angry associate taking out frustrations on fellow employees. If you understand where your coworker's anger is coming from, you will be able to better deal with the situation.
Evaluate your response to them. Many times, when we are upset at a situation, we tend to direct our anger at an individual rather than the situation. Take a step back and see if the way you are behaving may be influencing how your coworker responds to you. Before going to a difficult coworker to discuss a point of contention, rehearse what you will say in front of a mirror. This way, you can see if your approach is genuinely for the resolution of a problem or if it seems you merely want to provoke a disagreement.
Always follow the rules of common courtesy and treat your coworker how you would want to be treated. This way, others may observe you did nothing to provoke any sort of anger from a difficult coworker, but rather simply minded your own business. You want to be able to say you did not provoke any sort of ill-feeling or stoop to underhandedness, even if your coworker does.
Document everything. Whenever you are dealing with difficult individuals, there is always the chance they will try to make you look as bad as possible for their benefit. If you have proof of your behavior and your doings, this will greatly help your case.
When dealing with a troublesome coworker, keep all records of correspondence. Save all emails back and forth between you and this individual. If your difficult coworker brings up a particular incident or references an email, you can show your side of the story too and provide a correct copy of the email.
Consult with HR. While you may try to deal with a difficult coworker, sometimes matters are simply out of your hands and need to be referred to HR to handle. This is where your saved documents on your dealings with the coworker will come in handy. Supply all evidence truthfully to HR so they can deal with the individual in the proper way.
Don't make the situation worse by being just as difficult as your coworker. Document all dealings with the difficult coworker.