It is unusual for a JW to become a close friend with a 'worldly' person. And that is how every person outside the religion is referred to. Perhaps you expressed an interest in his beliefs in the past? That is the main motive I can think of for him drawing close to you.
The JW movement is often described as totalizing, they believe they and they alone serve God and that everyone outside the religion is influenced by Satan and will shortly be killed by God at Armageddon. Hence the world to a JW is a dark and dangerous place and they are not to make friends with 'worldly people'.