What on earth is going on at NaNoWriMo HQ? Here's a high level summary compiled by an anonymous community member.
Sidekick
A sidekick is an imaginary friend that can be adopted when you write. Sidekicks work similarly to Adoptables, except that sidekicks do not necessarily appear in your novel, instead sit by your side while you write, much like an imaginary friend.
The exact origin of sidekicks is unknown. They appeared the form of Word Count Angels and Word Count Dragons in the Adoption Society forum as early as 2011, possibly earlier.
As of 2019, sidekicks have their own Sidekick Stable forum (er, stable).
How Sidekicks Work
Wrimo Saving Annabel wrote a quick Q&A on sidekicks in October 2018[1]:
So how do Sidekicks work?
Sidekicks are like imaginary friends. They're our sidekicks when we write. NaNoWriMo Angels keep us from erasing words, Research Phoenixes help us with researching, etc.
Do you just say what one you want to adopt and that's that?
If the Sidekick isn't adopted and you want it, then, yes, you can ask to adopt it. If it has already been adopted or you just want to make a request, you can ask if someone has a Sidekick they're willing to give. Someone might give you one.
What do you do once you've adopted one?
Just imagine the Sidekick with you and have fun. If you don't want it anymore, you can give it back for adoption. I recommend making a new document just for your Sidekicks. Copy and paste what the Sidekick is and (after you adopted one) its description.
I'm using a Setting Seal from the Adopt a Setting Seal thread for example:
(What it is) Setting Seal
Do you have an idea for a story but having trouble with worldbuilding? Need help making settings for scenes or describing the place? Setting Seals could lend a hand- or a flipper.
(Its description) Harvey has fuzzy white fur with multi-colored tiny spots all over him like paint splattered from a brush. His eyes are blue, and his height is about knee-length. He loves chocolate, friendly, and is curious. Harvey doesn't have any preference for genres.