i've co-written with 3 different people, and we've handled the process a bit differently each time. swellow and i talked a little more in-depth about how we co-write no other homeland a while back here, but i'm gonna answer this one more broadly!

i've always made sure to co-write with people who i really get along with, and importantly with people who i know share a lot of my tastes in terms of tropes and ships we like. i always know that we like reading a lot of the same things, both by talking to each other about fics we like and by seeing that i often like the fic they rec, and i know that they tend to write the kind of fic that i also like to write. i say this just bc i don't necessarily think it's enough to just really like the other person's writing: there are lots of authors whose fics i love who just have very different writing interests from me, and i suspect it might be more difficult to collaborate if we didn't have some overlap of our comfort zones.

as far as like the actual process of writing, it's turned out a bit differently every time. my first co-writing partner was my bff angel and we've written a couple of things together over the years (not on ao3 though, those fics live either only on tumblr or privately in google drive as gifts for friends of ours), and for those we usually write out of order and we'll each take charge of single scenes or even entire chapters, so we work fairly independently. we'll often end up both contributing to each other's sections though bc we just talk to each other a lot throughout and will invite each other to add to certain parts or to take over if we're unsure where to go next. with swellow we alternate writing small chunks within a scene (500-800 words typically), and usually we'd be in our shared google doc writing live at the same time, which i think helped with consistency and flow! though recently our schedules have been more unpredictable so we don't sit in the doc live anymore, but we do still alternate chunks and just let each other know when we've updated. and with beebalm on unfastening we're somewhere in between those two methods! we usually each write fairly long chunks (something like 800-1500 words), still alternating within scenes. sometimes it takes a couple of days for one of us to finish up the section we're in, so if we update it we'll just tell each other like "hey i added some stuff but i wanna come back and finish up later!" so we know to wait for each other to be done before the other takes over. just talk to each other about the process and be willing to make changes until you find something you're both comfortable with!

i think the most important thing to co-writing successfully is being able to communicate with each other honestly, specifically, and kindly, and also getting into a bit of a different mindset where you recognize the fic as Ours, not Mine. like, i think i'd have a terrible time just deciding to have someone guest write a chapter of one of my wips, because i have such a singular vision for those and i feel so much ownership over them, it would be almost impossible for me to feel satisfied with what someone else wrote for it. but with all the fics i've co-written, we've developed the outlines together and begun the writing process together, so i don't think of them as My fics really! they belong to both of us, and so i'm a little looser with them because i have to be open to someone else changing things around or adding to them without getting offended or possessive, y'know?

like, even though we talk about fic trajectory and scene outlines before we start writing, there are always points where one of us will kind of take it in a different direction or do something unplanned, and when we do we'll let each other know and discuss it usually. i think it's important to be able to recognize within yourself how attached you are to something you've written and then to be able to effectively communicate that to the other person. so, for example, if i'd made an unplanned decision in a scene, i might say something like "okay SO i went in a different direction but idk if i like it yet, so let me know if you wanna change it or can't get into it" for a change i'm not too attached to, or "i changed something but i think i actually really like it this way, i was having a hard time with the previous version" if it's something that i really like and want to advocate for. i don't know if i've ever encountered a scenario where i wrote something that is so precious to me that i wouldn't want to change at all, but if i did i'd also let them know that too! that way when we discuss it, we know how gently to treat it if one of us does wanna make some kind of change.

we have to feel comfortable shooting down each other's ideas or changing directions in a scene without walking on eggshells or worrying too much that we'll hurt the other person's feelings, and i also think it's CRUCIAL to be able to communicate in SPECIFICS! rather than just saying "i don't like that," we need to be able to say what we don't like and why, so that it feels like there's room to move forward. for example, in unfastening especially we have SO many ideas for it that both of us have had multiple ideas we've tossed at the other person regarding future story beats where the other person has replied like "i dunno how i feel about that, i don't think they're ready for it" or "but wouldn't that complicate [x]" etc etc. and you have to figure out that right way to say that, bc just responding to someone's ideas with "i don't like that" doesn't give you much room to move forward or compromise! it makes the other person just feel shut down. whereas if you can communicate exactly what you don't like about something, there's room for the other person to propose a fix or to know what kinds of ideas to avoid pitching in the future. usually we will be clear about what we like about the idea and also about which part of it gives us hesitation (e.g. "i love the drama of that, and i like the idea of adding in another angst point later, but it feels like maybe it's too much angst and it might complicate the plot in a way that might be difficult to resolve.")

sorry, i wanted to keep this fairly short but i've made it SO long lmao!!! but the tl;dr of it all is that i don't think it's bad to be really sensitive about your writing or really attached to your specific vision of your fic, but that if you are, you need to recognize that and maybe avoid co-writing!! writing is very personal, and it can be really easy to respond to ANYTHING that isn't 100% positive by getting defensive or hurt. it makes sense! but also, it's not conducive to writing with a partner. and i also think that just brainstorming a scenario with a friend is a bit different from the process of sitting down to write it together! it can get more prickly once you've started actually crafting it and possibly needing to change things, especially when both people need to be entirely on board for something. you need to both be comfortable with saying no AND be comfortable with someone else saying no to you! and honestly, those things are hard for a lot of people! so if they're skills you struggle with, communicate that! e.g., i struggle with transitional scenes and i tend to get down in the dumps about fics once i get past the opening, and i TELL my writing partners those things, so that if i'm unhappy with something i can be like "this might pass, it might not even be the fic itself, it's just me struggling with something i always struggle with" so they know not to take it personally! but i've always had a lot of fun doing it, and i've been lucky in that all my writing partners have been really easy to communicate with and very understanding. i love all of them very much!