Understandable. I don't plan on profiting off of it.
This is
THE biggest misconception in copyright/trademark law. I really wish people would educate themselves on the topic and stop spreading this nonsense.
Profit has absolutely zero to do with whether or not you've infringed on someone's rights with regards to their whatever, be it intellectual property, image, name, or whatever else is intrinsic to their brand, business, or product. Nintendo shuts down "not for profit" fan games all the time, and Back in the Day, 20th Century Fox was so zealous about shutting down Quake mods featuring their IPs that for a while the community called being serviced with a Cease & Desist over IP violations "getting Foxed".
So. About celebrities.
Celebrities often (nearly always, at the level of fame we're talking about) own the rights to their likenesses/image and name. You're often not allowed to use any of those things in a work - for profit or no - without express permission of said celebrity. I know this for a fact because I've worked on projects where this was an issue. The main thing is, are you using the celebrity as a "draw" to your content? I'm guessing you are, otherwise you'd just make up a random character and call it a day.
That said, the average celebrity (and their legal team) has bigger fish to fry than horny dudes on the Internet putting them in slash porn. You're not going to get a "copyright strike" for a text story, and unless you're asserting the tale is true in an effort to get something out of it (and often even then, after all the National Enquirer is still in business), you're not going to get hit with a defamation lawsuit. Even if you are in violation of one of these laws/policies/statute, unless the celebrity in question can prove actual damages or you have a lot of assets to go after, such things would fall under what's called "blood from a stone". IE, they can't get any. At most you might get a C&D in an effort to scare you.
I'll bet you're wondering though - because this is the other defense people like to wield like a magic wand - "can I just call it a parody? That's protected under fair use, right?". And the answer is no, there are few to no ways that the average tick-fic would fall under parody in the eyes of a court.
So yeah, "you creeped out my client" isn't a valid legal defense, so while what you're doing might be sketchy depending on who you ask, you probably won't get in legal trouble.
None of this is legal advice. I am not a lawyer, I just know a lot of people of varying levels of famousness. Proceed at your own risk. blah blah blah
