How do I politely tell a mutual that I have absolutely no interest in a few of the characters they keep trying to throw at me? I have so little interest in the fandom that I have interest in even doing an au with the characters tbh but I feel like an asshole...
Your consent matters in roleplay! If someone's trying to foster interest in a muse or characters you've got little interest in, just be direct.
Something as simple as-- "I'm going to be honest, I have little interest in those characters. Perhaps we can plot something else with X or Y characters instead."
You shouldn't be afraid to say no to a roleplay partner. Agreeing to write with someone doesn't mean you are obligated to interact with every single one of their characters. You may be unfamiliar with a series, have little interest in that subject matter, or outright be uncomfortable with the fandom.
And sure, there's the chance that they'll take offense to it. But that's not your problem. You are not responsible for how someone else reacts to your declination. Offering to interact with them in an AU is a great means of compensation, and more than enough to go on. If they don't want that, then you just-- don't write together. It's that simple.
It sucks when someone doesn't want to interact with specific characters, but you cannot force a roleplay partner to write with a specific muse. CONSENT MATTERS on both sides of the conversation. Flexibility in having a writing partner is key.
And if someone is disregarding your consent and comfort, BLOCK THEM. You don't need to announce you're doing so-- you can just-- block them and move on. You owe no one an explanation. If you feel like you're being disrespected, then protect your peace.
That being said-- it is also good form to try and find some common ground. I've personally had folks ignore my OCs in favor of my canon characters frequently. It can be really frustrating, especially when they only want my canons to write against their OCs.
Truth be told, I've blocked and terminated interactions with folks like that. If you want someone to write with your OC, then you should write with theirs, too. Roleplayers are not machines here to play out your fanfiction dreams with. We're all humans with our own needs, wants, and desires.
A little compassion goes a long way.
As always, the askbox is open! For clarification on answered queries, or for further questions on RP meta and whatnot.