The Birthright Gate

Question: Would it be possible an Annuna Scion to get a "true" Mushushu as a Birthright creature, and if so how many dots would it cost? What about the "fake" Mushushu from Companion, how do the Annuna feel about giving their Scions one of those for a pet?

I don't see why not; I'd allow it as a Birthright, probably granted at Demigod, if it made sense for the character. (I wouldn't allow it at Hero, since we don't allow creatures to be closer than two Legend behind their Scion and there's no such thing as a non-Legendary mushushu). It would probably need its stats brought down a little bit to put it in line with Nemean beasts of a similar level (and I'd give it a dot rating equal to a comparable Nemean beast), and you'd need to come up with who got it for the Scion and why - maybe Marduk had one stuck to his boot that wasn't quite dead one day, or Ishtar has been keeping some as pets, or what have you - but past that, go to town. Mushushu are very cool and very Babylonian, so they make a perfect companion for a Scion of the Anunna. Some of their powers might not be very helpful to its owner - in particular, the ability to call other mushushu, most of which probably wouldn't be friendly if they showed up, has the hilarious potential to go very badly - but hey, those are the risks you run when you hang out with what are essentially small, bad-tempered dragons.

The mushhushshu from Companion confuses me, to be honest. It's a toothy dragon-creature, but you can't use it in combat because it's not actually any good at fighting? So instead it's intended to be a mount, but that doesn't make much sense, either, considering that Scions are going to be able to easily outstrip its speed on their own if they invest in Epic Dexterity. As it's statted in the book, the poor thing has only two dots of Dexterity. There are humans who are faster. The draw, the writeup says, is that it can carry the whole band and isn't upset or distracted by crazy things happening around it, but you could get the same effect out of a Nemean creature with some Epic Dexterity or, you know, someone with a couple dots of Epic Dexterity and Strength who can just carry their bandmates. And both of those options would be a lot faster (not to mention possibly able to fly thanks to boons or other natural features or powers, something the mushhushshu in the book also can't do).

So I don't really know what the mushhushshu in the book is supposed to be doing, because it seems like one of the most useless Birthright creatures ever. I can't imagine any god-parent, let alone an Anunna who has seen a real mushushu, wanting to give one to their Scion without very specific reasoning, which is why our Anunna supplement suggests that they're confined to pantheons without any understanding of what a real mushushu is supposed to look like or do.

However, if you wanted to give a Scion one of these gigantic (but probably fun!) wastes of space, you could always have it be a gift from a god of another pantheon, possibly trying to get in good with the divine parent, already his or her friend, or even as a prank (in fact, other Anunna, if they were so inclined, might find that kind of pranking entertaining). I can just imagine the hilarious look on Marduk's face when he sees his kid cuddling one of those monstrous and useless things because Grandpa Enki gave it to him.