How should I talk to an unwelcoming future research group colleague so no interpersonal issues raise? This year, I am going to join a research group in which one of my past classmates who used to study in the same university during my the bachelors degree years is also working. The professor who is going to supervise the position is completely supporting my attendance and likes my resume. However, that friend of mine reacts not so friendly. He does not answer my emails or even quick phone calls which I wanted to check the correct paper work or document submission process. Even the content of his conversations is not so friendly and warm.

That friend has nothing to do in my attendance (before I know he is working there, I had contacted the professor to talk about the position) and our research topics will also be different.

I am worried on how I should possibly deal with such person in a research group who seems not to be welcoming to me. I mean, how should I continue my connection with him, so that no interpersonal issues raise here which may affect my performance in that group and position.

Should I completely ignore such person or try to behave constructively; for instance, for easing the connections and trying to make warmer friendship, should I try to call him and discussing topics, try to talk about my attendance there, etc? I am worried, since it seems he is not happy with me attending that group and he is a senior person (he works there for about three years), he does not allow me to have my best performance, connections and cooperation, etc.

Although, I have a sense that I am overthinking this issue and the condition may not be that problematic since the professor likes my resume; I need to know how to successfully behave to that person so that such possible misunderstanding be solved and we have good days in our office in future.
From your description, I'd say it's not time to worry yet:


Meanings convey poorly via words. See e.g. this "joke" that turned out to grievously hurt someone. You can't be sure your former classmate doesn't welcome you ... yet.
It's possible you're asking your former classmate the wrong things. For example you're asking about paperwork. Why should he know the paperwork better than, say, the professor or the department receptionists (or you for that matter, I'd expect the paperwork needed to be on the website)? He could be annoyed you're asking him questions you should ask someone else, which should resolve itself if you stop doing that.
He might simply be going through a bad period. For example if he just broke up with his wife and is fighting over the divorce agreement, you can't expect him to be very enthusiastic about anything.


If you're keen to join the group, I'd say join it first and only start worrying if it really doesn't work out.