Batman will settle into a bit of a pattern, then, as she makes her way through the castle, stopping when she stops, walking when she walks, pricking his ears up at every sad little sigh. From the glimpses he gets of her, it seems very likely to him that whatever she has in the bundle has to do with what's bothering her.
After a while he notices they seem to be approaching the center of the castle.
Let me know if you ever need more to work with btw
After a while he notices they seem to be approaching the center of the castle.