Rising Tides by Marion G. Harmon
In the world of Wearing The Cape, but a new character, and not even one as closely related to Astra as Artemis. Parallels the events of Repercussions and Joyeuse Guard.
Kingston's new job crashes and burns as it turns out the company was corrupt. He's heading home when the attacks come. He flees. He flees quite well. And it takes him a bit to realize he's teleporting -- he's a breakthrough. And his best friend and roommate really hates breakthroughs.
It involves a job-search, several characters from Astra's series, laws against breakthroughs, rats, tests of his ability, and more