Yulebuilding 2018: Worldbuilding for Yuletide

[extrapenguin]

Greetings, everyone! Yuletide contains multitudes, and a chunk of those multitudes would really like to request worldbuilding. Thus, here is a sub-challenge post for those of us who love worldbuilding, either on the giving or receiving end.

To participate

• Leave a comment on this fic with a link to your letter if you are interested in receiving worldbuilding. Optionally, add any extra worldbuilding likes, DNWs, and prompts you may have into your comment.
• If you don't have a letter, you can still leave prompts here! Please ensure your comment includes your AO3 username, requested fandoms, and any characters you're requesting.
• When uploading your fic to the archive, tag it with Yulebuilding and Worldbuilding so the rest of us can find it!

It's not necessary to interact with Yulebuilding in any way to give or request worldbuilding for Yuletide, but this post is here to make life easier. Enjoy!