Finnick can make himself very quiet. It's a skill he's developed since being free. He's seen when he wants to be and next to invisible when he doesn't. That's how he sneaks up right behind Ringer.

He doesn't know who or what she is, but there's a dead body and he knows there was a vampire nearby here recently. This particular vampire has made meals of a few fae and Finnick's determined to put a stop to it, which is why he's out here with his trident which he's now pointing at Ringer's back.

"Don't move," he says, quiet and steady.