Anything of mine written after 2007 is open to remixes, sequels, art, podfic, etc. Go nuts, don't even have to ask. I would like it if you'd drop me a link so that I can add it to the fic's notes, though! Or, if you're going to be posting it here on AO3, I'd really, truly, sincerely appreciate it if you linked to the original story in the "This work is a remix, a translation, a podfic, or was inspired by another work" box.
Pre-2007: Is not my favorite of my work, and I'd prefer it if you kept to remixes only.
Preggers. Because that was co-written, please ask Vera for her permission if you want to remix it.
So I Guess He's My Boyfriend. Also co-written, but my co-author is no longer in fandom and would prefer not to be named or contacted.
I would prefer that derivative/transformative versions of my fics not be used in gift exchanges without asking, and if it's a fic that's labeled as a gift for someone else, I'm sorry to say that the answer will most likely be no. My gift fics are intended for their specific recipients, and I'm deeply uncomfortable with the idea of them being transformed and re-gifted to someone else. There may be exceptions (e.g, if your intention is to give it as a gift to the same recipient, or if the original recipient has left fandom), but I'd truly appreciate it if you were to contact me to discuss it first in that case.