With the "Turf Protector" type of person, you need to listen behind their words to determine what they are trying to protect. Most argumentative or negative people are not trying to attack you as much as they are trying to protect their world as they know it.
Because they desire so strongly to protect their own world, they will gladly argue or defend their point of view. So the first thing you should do with an argumentative or negative person is to try to figure out if this a habit or paranoia.
Here’s the difference between the two. If it is a habit, a person will often fluctuate between being argumentative and being agreeable. You will notice that even in their daily conversations, they will focus more on the negative aspects. Ask them how their golf game was, they say it was lousy. If you ask how they enjoyed the movie, they tell you that they’ve seen better. Even in friendly conversation, they react in a negative manner.
This differs from the individual who’s paranoid. This person has a tendency to look for the evil, twisted, or hidden meaning behind what anyone says. If you run into this type of individual, run as fast as you can. It won’t matter how you say things, they will always find the twisted side and turn your words against you.
The first individual, who tends to be argumentative or negative out of habit, can be brought around in a very positive fashion. What you need to do is ask him only questions that can be answered positively. For example, “Share with me three features about XYZ that you really liked.” or “What did you do for fun this weekend?” By directing them with proactive questions, you will start helping them to socialize in a more productive manner.