Most Helpful Guy
You will have to make him feel more comfortable around you. Sit down next to him pretending like it was not on purpose. Meaning, there was just no better seat. Say hi, introduce yourself, and ask how his day is going. That will make him feel comfortable having a simple chat with you. Try to find a topic you are both interested in, and go deeper into the topic. If he is familiar with a topic and sees that you have interest in it, he will open up and be comfortable talking to you. When you two are done, say that you had a great time and that you two should do this again someday.