The use of indirect resistance or retaliating attitudes that avoid direct confrontation is not rare in our workplaces. It’s always bringing a negative effect, but to deal with a passive-aggressive coworker at the same level with you is a lot easier than a supervisor. At least you would still have some space to deal with the attitude. This does not suggest that reporting him or her to your supervisor is the solution. You have a big role to play when your coworker is passive-aggressive, whether s/he is your supervisor or not.
The sarcasm, hurtful remarks, and other stalling tactics to vent their anger can be very annoying, but you must be really matured on this one if you wish to go through it swiftly. Even if you're the kind of person that reflects people's character towards you, this time has to be different.
Try to understand the reason
Understanding why your coworker is passive-aggressive is essential as you deal with it. Secondly, you should know that a passive-aggressive coworker is picking on that behavior because he or she is angry, perhaps because of jealous, change of office routines, reduced workforce, office relocation, etc. This knowledge will also help you to deal with the relapse and also in tailoring information that could reach the passive-aggressive coworker from your desk to minimize the aggression.
Don't respond in the same manner
You should understand that the passive-aggressive coworker is seeking a solution through the wrong means and need help. Some people think it's a good thing when your coworker is passive-aggressive. Take your time to respond to his or her actions, don't be quick at all. You may be successful if you use empathy, go subtly and stand down. Two aggressive heads will not bring any solution or help your reputation. Yes, take your ego away, please. And wait for his or her better moment. You may just break through after a short while and turn out to be best friends because you showed maturity.
Be open for communication
Don't turn off your communication mood because your coworker is passive-aggressive. You may be asking why you'd have to take all the insolence because you're the good head here and must pioneer all measures to remedy the situation. Inform the passive-aggressive coworker you're available for a talk on Skype or other responsive means of communication aside from your office email. And be willing and ready to talk when you get a message from him or her.
Allow other coworkers to see the situation
It’s good that you allow other colleagues to understand that your work relationship with the passive-aggressive worker is not poor as a result of your decision. Show that you can accept him or her not to like you but you’re respectful and expect the same. Try to contribute freely to a conversation he or she is involved in, this will help to show you're not holding up grudges for the behavior and willing to have peace.
If all your efforts for a solution remain futile, and the passive-aggressive coworker is sabotaging your work intentionally, making your workplace unsafe with threatening comments, please report to your HR department. But before reporting, take note of some of the aggressive statements as examples to share as you file the complaint.