Louis notices the change in Kaworu's step as well, although for him the determination to fight comes from the fact that the creature he faces is a threat to those he cares about. If it's allowed to escape...it will hurt them, he can tell.

His heartbeat is getting louder. It's also getting faster, but it doesn't feel dangerous. More...normal. And then...there's a voice, whispering in his ear. He straightens up, trying to see it, but there's nothing to see, so he glances over at Kaworu instead, inclining his head as the darkness approaches.

Can you hear it too? he's trying to convey.