Still decent writing but still some mistakes.
The sentence "To my surprise he didn't look that surprised" sounds, quite frankly, pretty stupid. You can't really use two words like that in the same sentence. Try using a different word for surprised eg astonished, shocked, etc. Also there are a lot of "mikes"' that should be "Mikes"' and a lot of "gee"s that should be "Gee". Also, if I were you I'd make the little voices in Gerard's head italic so it's easier to read and "Cute Mikes" should have a comma after the "cute".
Finally, "half a brain cell" doesn't really work as the brain is made up of a lot of cells and if one of those cells was missing half of itself it could still fuction okay. "Half a brain" works though.