In Castle The Attic how can you describe William?

It's impossible to describe William from "Castle The Attic" without more context. There are multiple "Castle" series, and "The Attic" could refer to a specific episode or even a fan-fiction story.

To give you a helpful answer, please tell me:

* Which Castle series are you referring to? (Castle, Castle: The Series, etc.)

* What episode or story is "The Attic" from?

* Is there a specific William you are asking about? (For example, William Beckett, a character in the TV series, or a different William in the story).

Once you provide me with this information, I can give you a description of William.