I have an iphone 5. How do I turn off imessage for an individual on incoming messages?

I don't want him to be able to see when I pick up the messages. But at the same time, I want to keep imessage on for others.

You can't. Sorry!

You can go into imessage settings and turn off "read receipts" you can still read the messages, but he will never know that you looked at them

If you turn off read receipts EVERYBODY will not know you looked at their message, not just this individual