What does it mean when a guy is more talkative when he initiates instant messages with you rather than when you initiate instant messages with him?
I would suggest that it means he has more time to talk when he
contacts you. Perhaps you IM him while he is at work, or he is
watching the Superbowl, or driving. Maybe when you IM him your
first question should be to ask if now would be a good time to
talk, or maybe he could get back to you when he is more able to
talk. It could mean that he's in the middle of something and
doesn't really have a lot of time. When HE initiates the
conversation it's probably when he has free time.