Let him be. He will come out when he feels secure. I have an Exquisite Fairy Wrasse (Cirrhilabrus exquisitus) in QT right now. He's super sociable and swims up to the glass when I come in the room. However, it took him more than a week to come out from behind his PVC and swim in the open for long periods of time. Just keep stress to a minimum and he'll come around.