Set the stage by letting them know how much you value their partnership and that you want to collectively figure out a better way to work together. Bring specific work-related personal examples to the table and use simple, common words to describe how you felt about their behavior and actions. Then offer to brainstorm and work together on specific outcomes that will help reduce the toxicity.

Name specific examples

If a person is always pushing in a different direction, they are making it difficult to reach your objectives and achieve your vision. You should follow the process, document all interactions and inspire the person to correct the behavior. If they do not correct their path, it's time to take action.

Document All Interactions 

Due process exists so that personnel-related liabilities do not go unaddressed. Leaders and HR should assess the severity of the behavior, and assuming it's still salvageable:
<ul>
<li>give constructive feedback</li>
<li>record and document these discussions</li>
<li>monitor the team member's progress</li>
<li>take the temperature from their colleagues and department heads</li>
<li>evaluate what additional measures need to be taken.</li>
</ul>

Trust Due Process

Instead of avoiding the person, seek to address the issue head-on because, if left unaddressed, it’s only likely to get worse. 
Ask for a private discussion with the other person to express what you’re experiencing as pleasantly and agreeably as possible to avoid damaging the relationship further.

Ask For A Private Discussion

When faced with someone who is challenging or toxic, the first step is to understand what is motivating the behavior. Only then can you apply some authentic understanding which can potentially turn a relationship and allow you to be the one person who breaks through.

Understand Their Motivation 

Define your boundaries when unacceptable behavior transpires. For example, when intimidation occurs, say, "Are you trying to intimidate me? If so, please stop. It is not acceptable, and I will not engage further if it continues." This typically stops the toxic person because they do not want to own up to their behavior.

Define Your Boundaries 

You’re trying to make the relationship better, so don’t jump to conclusions, be petty or accusatory. State what you’re experiencing in a non-threatening way and follow it with a question. 
Here’s an example for a micro-managing boss: “I’m really excited to be working on this project. I’d like to try a bit more soloing. Would you be comfortable with that?”

Start With A Casual Conversation

All people deserve to be treated professionally and with dignity. Remembering that being direct is not in contradiction with professionalism is imperative. Be direct, brave and respectful.

Always Be Direct 

When a difficult colleague is someone demanding control and influence, one effective tactic is to feed him or her a steady stream of status updates. Keeping these colleagues in the know helps them accommodate change more easily.

Keep Them 'In The Know' 

Focus on effective communication. Professionally communicate through various channels (email, phone, text, etc.) and see which channels produce the best result. Proceed with those.

Try Different Methods

For difficult personalities, communication is central to meeting expectations and resolving conflict. Understanding what drives the individual and what is important will allow you to more effectively work together. 
However, the behaviors of toxic individuals need to be addressed immediately, perhaps through human resources intervention.

Difference Between Difficult and Toxic

Tactics for when things get tense at the office to help you diffuse the war at the water cooler.

teamwork

Teamwork

leadershipandmanagement

Leadership & Management

loveandrelationships

Love & Relationships

communication

Communication

personaldevelopment

Personal Development

De-escalate Office Tension

When hiring new talent, most employers try to match their company's values and culture with potential employees. However, in a diverse office with workers of various interests and personalities, it's not uncommon to experience occasional tension. Toxic personalities aren't always obvious in the hiring process, and they may emerge well after an employee has been onboard.

Understand Their Motivation

Similar ideas to Understand Their Motivation

Understand people's motivation

A Final Word of Advice

Learning to speak up: taking an outsider's perspective