WEll my first thought was to darken the background and then i wanted to dulicate just hime and put him in a bubble like he was thinking outside his head. As you can see below that idea didnt work so well. that or its 3 a.m and i'm too tires to think very well.
so what i did was take the selective tool and set it to edge seeker and 0% feather and trace around him. copy and pasted onto new image. Oh and I did lighten him up little first by going to brightness/contrast and lightened him up by 20%.
Then on the new image i again used the selective tool and traced around the rock and part of the girl and copied. Went back to the layer with his picture on it and selected the pick tool and moved him where i wanted thought would look good. Then I pasted the rock and girl as a new layer and placed it over him and as close to the orginal as i could so no lines showed.
Went to orginal layer and softened up the edges a hair where it didnt look so hot and then merged all. Oh and just for fun, I used the warp tool and set it to expand and kinda made thier chests bigger. I said i was tired and delirious didnt I? lol