Totally bro! Let me just post that to this public internet forum for you...
UPDATE: No, that was a joke. I was referring to imagery, which fictional or not can definitely be illegal in the USA even if you draw it yourself in your private journal.
I'm not sure if you can be prosecuted in the USA for anything you write down yourself and don't somehow disseminate. (Although "doing it with computer" might also change the equation... US laws get pretty weird.)
Despite the wording of certain bills, mere possession of purely artificial media is generally not something the government has or can demonstrate a legitimate interest in controlling.
Calls for violence against corrupt and powerful people who abuse others on a daily basis.
Classified or confidential information such as security plans for the previously mentioned powerful abusers. Also including educational and medical records.
Ways to circumvent censorship (DMCA.)
Releasing true fact against court orders.
Publishing factually correct evidence of powerful people raping kids (CSAM.)
Publishing decryption keys that allow government information to be accessed.
Software without FBI backdoors installed.
Information that encouraged disobedience to current law (e.g., sovereign citizens.)
Trade secrets.
Communicating anything over radio frequency without the correct FCC license.
None of that is illegal to write, some of it isn't even illegal to communicate. Most of the things there would only create a legal issue when communicated, but not when written, and in most cases are necessarily written by authorized persons.
Trade Secrets are basically always written down, they are not illegal to communicate, but doing so may violate a contract which would be a civil matter not a criminal matter. In the cases that the contract is either determined not to be binding or expired or was otherwise nullified, communicating trade secrets is an expected outcome. In fact, what makes something a trade secret is that a business takes actions and expends efforts to prevent its communication, as opposed to publishing it openly as a patent and getting legal governmental protections.
