BUR #7610 has been approved by @nonamethanks.
create alias pixie -> fairy
create alias faerie -> fairy
I think that technically pixies are 4 inches while fairies are 6 and faeries are evil, pixies are mischievous, and fairies are good.
But for Danbooru's purpose, they're pretty much all the same.
Pixie currently has 42 posts and I can't see any difference between them and the fairy posts.
The faerie alias is a utility alias because that was the first term I thought of while trying the find the tag.