[Well, it seems about time to explain. Eren hops off of Maruki's hand and soars up into the sky again, just for a few more minutes before he has to change back. As he comes to land, he transforms back into the Eren Maruki met (stumbles a little on the landing - whatever). Not only is he fully clothed in his usual outfit (casual, long black coat - not his Scout attire), but he's apparently armed with some strange weapon, as well.

[He starts up conversation again, casual as anything (his mood has gone back to its usual disenchantment, as well).]

I drank the gold potion when I first got here. I could only transform into a wolf at first. I figured out how to change into the bird myself, later. [The crystal helped, but he doesn't know that.]