Ruxala is a Wulfenbach Weasel Wrangler of the Vespiary Squad. Not only is she a wasp eater lover and trainer, it also turns out that she's a fierce warrior (at least against slaver wasps) in her own right.
She is one of the members of the Squad who defect down to Mechanicsburg under Tarvek's influence during the Siege of that city. She is thus on board the airship which is shot down by fellow Wulfenbach forces. Tarvek is helping her release weasels from cages in the ship when she is stabbed by one of the Baron’s Stealth Fighters. Since she is not immediately killed, he has to carry her out, along with Jorgi and a number of weasel kits. Despite her wound and being semi-conscious, she shows her aforementioned prowess by shooting an attacking wasp Warrior.
She survives all this, and is last seen hobbling around still wounded and using her remaining wasp eaters to scan people in Mechanicsburg, but finding an oddly low number of Revenants. While some members of the Squad slip out of the city with retreating Wulfenbach forces, intending to set up new centers of study outside the empire, she stays, and when last seen for the moment, is one of the witnesses ✣ in the Red Cathedral when Klaus drops into the city and activates his Take-Five Bomb.
Much much later, as Agatha prepares to remove the time-stop, Ruxala reappears ✣ outside the walls of the city with two other Squad-members and a swarm of wasp eaters, joining the upcoming expedition to reclaim Castle Wulfenbach from whoever has commandeered it; we then learn that she just barely escaped the time-stop thanks to Sergeant Scorp appearing with a couple of (ahem) conveniently speedy horse-type mono-wheeled vehicles. (Scorp didn't make it, and got stuck in the time-stop.) Ruxala is then rescued from other Wulfenbach forces by Dimo and some Jägers, who also manage to save a few other Squad members from the Wulfenbach purge, and hide them all in deep cover in the nearby refugee caves.