Seems like they're preparing a new part of Time Temple.

It is Freed and Afrien. The whole Mercedes promo is shown right when you create the character. After the huge bang at the end, Mercedes wakes up beside the two she was fighting with. Their names are Freed and Afrien, it's written right underneath them.

Well that settles that.

I think that the length of 9th and 10th groth Mir should be as big as Afrien, just that we don't want a Dragon that BIG following us all the time, right? From everything, I would say that Mir is indeed as big as Afrien, just that for playing purposes he isn't THAT big.

So...
Mir is big.
He just isn't when you're playing with him.
That makes total sense.