Rivetjaw Rivetjaw is a Class 4 Behemoth with one job: biting. Its jaws close with enough force to shear clean through mech armor, and they don't let go. It came out of the bay onto the docks and tore the plating off Crimson Howl's left arm like it was wrapping paper. The bite Most Class 4s are dangerous because of their size or their armor. Rivetjaw is dangerous because of its mouth. The jaw is the biggest thing on its body, hinged deep and driven by muscle that bulges like cable under its plating, and its teeth sit in rows like the rivets on a ship's hull. Once it bites down, it doesn't release. It locks, braces and twists, the way a crocodile drowns its prey. Anything it catches comes away missing a piece. How it fights Low and close. Rivetjaw doesn't care about range and doesn't try to stay out of reach. It walks into gunfire with its head down, takes the hits on its plated skull, and goes for whatever part of a mech it can get its jaws around. An arm. A leg. A shoulder. Every time it connects, a pilot feels it through the link. A mech that fights it from a distance gets worn down. A mech that fights it up close has to get its weapons inside the mouth before the mouth gets it. Specs Class: 4, Behemoth Built to fight it: Crimson Howl Spoilers: Rivetjaw Everything below this line happens in Season One. If you'd rather find out on screen, stop here. Rivetjaw hits the docks in the second episode, and Miko meets it in a Giga-Fist brawl, punch for punch. Those jaws tear Crimson Howl's left arm plating clean off, and Miko's own arm goes numb and burns for hours afterward. She answers by ramming the Plasma Lance down its throat and firing. She wins, barely, and climbs out with a split lip and a grin. Nobody else notices it at first: Rivetjaw arrived already wounded. Deep gouges in its back plates that no mech made, and no weapon in Kurenai's arsenal could have. It wasn't hunting the docks. It was running.