Shawn spent the last 4 years growing attached to his situation unfortunately. It took a while just like it will take a while for him to grow attachment back to being what it was like before he was stolen by Devlin.
There is another story of a girl from Wisconsin that went thru a similar experience as to Shawns. She was kept for 3 1/2 months in a series of hotels in Houston by her abductor all the while he went to work during the day. He masqueraded as her father. It is an interesting read.