Try either lucid dreaming:
Or the tougher but in my opinion better astral projection:
They are not technically "making the characters real," and will take some skill to learn, but it they are the closest you will get to what you are trying to do.
When you get inside, it is quite simple. after you have had some practice and have reached the state before, simply imagine them before you. for lucid dreaming it is tougher to get them to appear, but better nonetheless. Have fun!