Redditor I_Say_ writes, "My son wrote a letter to batman about a week and a half ago. Today he got his 'response'." You can view a larger version here.
Before you get too excited: Yes, Batman is real. But, no, he doesn't respond to letters. I_Say_ wrote this letter for his/her son. It's a fine job, though it does make Batman look a bit boring. I suppose that Batman doesn't have a lot of time to devote to fan mail. If he had only 3 minutes or so to devote to writing to each child, he's bound to resort to tedious platitudes that can be rattled off quickly.