Derek's mind was a very strange place. That much he knew. Unlike most people who could easily lose several hours focusing on one thing at a time, he often had several thoughts going on at once. He could be writing a report on expected profit margins while at the same time, looking at the expected profits and losses for the year, and then comparing them with those from the past years, looking for ways to improve without ever missing a beat. His brain was constantly processing, taking in new information and either storing it away for later use, or instantly coming up with ways in which it would be useful.
His mind was constantly in a take, take, mode, never fully resting, never stopping. And even the little naps he sometimes managed were not really restful.
