Reiner would know that crack of lightning anywhere. It feels as though it strikes somewhere deep inside, igniting his blood with energy, echoing with a power he can't access. His mind shouts for him to reach for that power all the same. To don his Armor and join his comrade on the battlefield, four years of war demanding he act as their shield.

Logic tells Reiner that the transformation isn't a comrade. He knows Eren is here. If he follows that crack of lightning, it won't lead him to an ally.

But … what if it does?

Reiner is running long before he makes up his mind. He has no plan for when he reaches the Titan; he just moves. His arms pump at his sides, and deep down, he hopes.

He skids to a stop as he rounds a corner, golden eyes wide. There are huge wolf-things—enemies—but that's not what holds Reiner's attention.

Porco, Reiner screamed at the end, helpless to do anything but watch. Here and now, his lips start to form the same word—a name he normally avoids, Galliard coming to him just as easily. But he doesn't get to finish saying the name, because at that moment, his instinctive reach for transformation finally bears fruit…

And in Reiner's place is a rhino.

A big, burly rhino that unleashes a deep, bellowing grunt before charging forward to join the fray, his horn ramming into a wolf.

(It's not his Armor, but at least charging still works.)