"Zetta's a god?" He has some trouble matching the fiery redhead that he'd accidentally tackled down onto the train floor with the dignity and poise that his world associated with the lost gods. Oops. It did explain his confidence in his own powers though, he supposed. He's never heard of Elfnein though, so he suspects it might be someone specific to Romeo's world.

Well, one thing at a time though.

"It's great that you kept up with it. 'f you want, we c'n practice it when we're together? I'm not super good at it yet, but it's gotta be worth a try!" And, well, there are more than one instance where sign language may be useful. Noisy surroundings, or trying to sneak without being heard-- Esteban hoped that he would learn more of it fast enough to help Amaya out during the next mission.