Co-writing is basically like role-playing, but with a definite goal and more structure. To ensure it goes smoothly, I recommend:

1. Set ground rules. Everyone likes to work a little differently, so have a chat about that. Will you both prefer to be in a Gdoc (I assume) at the same time, or to tag in when it's your turn? (Time zones may force your hand on this.) Will you prefer strictly writing your own character, or are you okay with the other person writing some things? How do you feel about your co-writer correcting typos and such—should they just do it, or should they let you know so you can do it yourself? What are your goals for your characters and the story in general? Communicate openly and make no assumptions except good intentions.

2. Make a plan. I find it helpful to copy the fic into a Gdoc so I and my fellow writer(s) can make notes on it, making jokes, highlighting errors, noting where things could happen to the agents, etc. You probably won't use it all, but it's good to have it for both of you to reference and not worry about forgetting things. Also, decide where you're going to end the mission and have a basic story outline in mind before you start.

3. Be prepared for the plan to change. Sometimes all the planning in the world doesn't result in the characters doing what you thought they would in the moment, and that's okay. You might end up with something even better!

4. Be prepared to edit. It's easy to fall into Talking Head syndrome and RP-itis (characters having multiple conversation threads going at once) in a co-write. You'll want to go back and make sure to flesh out any bare dialogue with description and action, and to make sure the dialogue proceeds like natural conversation. Also, co-writes tend to run long, partly because it's easy to get caught up in the fun of the characters bouncing off each other. However, a great RP isn't necessarily a great story. You'll probably need to condense or straight-up cut bits that don't actually pull narrative weight before you're done. If you really enjoy them, you can always have them as bonus outtakes at the end. {= ) Your beta(s) can help with all of this, of course, but having a go first yourselves is good practice.

And, I'll say it again because this should probably be Rule 0: Communicate! Communicate frequently, clearly, and politely. Communicate about things you want, things you like, and things you don't like. Don't expect the other person to read your mind. They can't, and waiting for them to do so will only result in frustration. And, always assume good faith. Remember that you share the same goal of telling a good, entertaining story, and that a difference of opinion is not a personal attack.

This will ensure that the fun stays fun. ^_^

~Neshomeh

I remembered I have an agent pair in Floaters. Since I created them mostly to prove a point, they're not very developed, so I wouldn't mind loaning the human of the pair, Caprice. She likes movie monsters, and she could also have a soft spot for Disney's Quasimodo. She may or may not even have read the original Victor Hugo novel. She appears in this faux–Permission piece and in the PPC HQ Hunger Games, Season 5.

She's your typical college-age PPC agent. I have it in mind that she may be Latina, two or three generations descended from immigrants to the US (not sure from where exactly). She's pretty cheerful, as you'll see from her appearances so far; I think she's probably more interested in touring the Multiverse and seeing cool canonical stuff than writing charges, and wouldn't mind Sues so much if they would just get out of the way. (In contrast, her partner is a persnickety, old-as-balls Nosgothic vampire who thinks drinking blood straight from the source is barbaric if not downright perverted.) She'd be happy to serve as a canon tour guide and point out interesting details about the setting and stuff—insofar as they get to see any, of course.

She might also tease Kaguya about resembling assorted creepy, pale, dark-haired ghosts. This thought amuses me. "Hey, did somebody wrong you so badly you were driven to infanticide in your old life? Is that why you're currently soaking wet and spinning on a golf tee with crabs pinching every other finger and your left ear?"

BUT, that's only if nobody else wants in. Please stop me from getting carried away and overcommitting myself. ^_^;

~Neshomeh

Just regularly watching animated Disney movies and having good knowledge of the continua is enough.