First off, the bullying behavior often follows that person into adulthood if it was never addressed.

Often it is still seen as a way to endure power over another person.

They don't often feel like they have control over subordinate figures. This could mean that you pose some threat to his/her position, or may have triggered something they commonly don't like.

Adult bullying is harder to see in the workplace sometimes but, nevertheless you still don't deserve to be treated in that manner. Sometimes, you can have a side discussion and bring up what you are seeing, and address the situation in its entirety.

However, What I would do is document everything in a daily journal after work.
 
If it goes to far you may have a court case against the company after you have brought it up. Once you bring it up, it can get worse because you identified their behavior as threatening to your position. 

Remember, it is the person that initiates the behavior that has the issue, and not yourself.

Bullies need not target their "victims" because they are weak. 

• You may just be in the wrong place at the wrong time. Bullies are predatory and opportunistic. 
• Being good at your job.
• Being popular with people.
• The bully fears exposure of their inadequacy and incompetence, your presence, popularity and competence unknowingly and unwittingly fuel that fear.
• Being the expert and the person to whom people come to for advice, getting more attention than the bully.
• Having a well-defined set of values which you will not compromise.
• Having a sense of integrity.
• Having at least one vulnerability that can be exploited.
• Being too old or expensive.
• Showing independence of thought or deed.
• Jealousy and envy are strong motivators of bullying.
• Unwarranted or invalid criticism while ignoring achievement
• Undermine in front of others, raise false concerns, or express doubts over a persons performance or standard of work, however unsubstantiated this may be
• Overrule, ignore and isolate a person from what’s happening.
• Regularly choose the target by offensive remarks and language or give the silent treatment. 
• Single out and unfairly treat a person differently to other members of staff.
• Degrade, threaten, or humiliate.
• Subject someone to unwarranted or unjustified verbal or written warnings.
• Set goals and deadlines which are unachievable or which are changed without notice or reason.
• Deny information necessary for undertaking work whilst others often receive more than they need.
• Refuse support if they are a manager.
• Overload a person with work or have all their work taken away and replaced with inappropriate jobs.
• Increase someone’s responsibility but remove his/her authority.
• Have work plagiarised, – the bully then presenting the target’s work as their own.
• Find requests for leave unacceptable and place unnecessary conditions, sometimes overturning previous approval.
• Send unpleasant or threatening calls or harass with intimidating memos, notes or emails
• Invite you to informal meetings which turn out to be disciplinary hearings
• Encourage you to feel guilty and to believe you are always the one at fault.

What you should do:

• Keep a journal of activity outside work.
• Approach the supervisor or coworker about the behavior.
• If this does not work take it to HR, the GM, or the company owner if small business.
• Remember, if you go to HR they cannot retaliate or even talk about it with others. Look for your harassment policy in the handbook, and utilize it to the fullest extent.
• If this hasn't worked see your local civil rights specialist, or seek an attorney and go to court with your documented case.
• As a last resort leave the company, because you don't deserve that kind of treatment. File a class action suit for lost wages, and seek mental health because, it may have caused psychological injury to you. If you would like to see what psychological injury does to someone, then read my story.
• DOCUMENT EVERYTHING!!!!