Captain Obvious Reveal: After three full books to tell us that the Mechanic's Guild lies to its apprentices and sets them up to trust nobody but the Guild, Mari is pretty much the last person to consider the possibility that the Guild simply lies about its apprentices being disowned and abandoned by their commons parents. Lampshaded in that when Mari explains the lack of letters and the Mechanic postal system to Alain, he takes all of a few seconds to figure it out.
Genius Bonus: Because the main characters do not understand the tech, many things in ancient/colonial-era tech are not explained, like what a Feynman Device is, or what Spooky Action at a Distance means, or why signals from Earth take 16 hours to reach Dematr. Readers well-versed in science topics, however, can figure it out.
Growing the Beard: The series was widely regarded as growing significantly better starting with The Pirates of Pacta Servanda. Some of the complaints of the first few books are addressed, including:
Several characters join Mari and Alain, which breathed life into an increasingly-repetitive dialogue.
The repetitive cyclic plotline of "Mari and Alain arrive in a new location, are immediately ambushed/walk into a trap/get found out, flee, repeat" is not only ended, but explained. Mari was unknowingly carrying a radio beacon in her far-talker.
Mari and Alain begin to formulate an actual plan, giving the plot more momentum and the protagonists more agency than the pair running for their lives and blundering into the book's plot.
The setting's Schizo Tech is finally given an explanation near the climax of The Assassins of Altis: Demetr is actually a colony populated by a spaceship sent from Earth. The Mechanic's Guild defied orders and set themselves up to rule by seizing all the tech that a young, cryo-frozen population was meant to use to build an advanced society.
Mari finally realizes that the Guild lied to her about her parents abandoning her, from which bitter feelings had prevented her from marrying Alain.
Harsher in Hindsight: Mari lovingly maintains her far-talker even though she has nobody in the Guild left to talk to with it. She sees it as part of her identity as a Mechanic. The Guild is using its radio signal to track her down and attempt to murder her. Even when it's turned off, it transmits on a very low power.
Hollywood Homely: While she's not traditionally "hot," Mari in the narrative describes herself as exceedingly plain and unattractive and even insists Alain is unlucky to be like her rather than someone like Asha. She escapes being painted as a mythological demon by propaganda because said demon is known for her beauty. However, Mari's artwork on the covers and in official art is perfectly well attractive by conventional standards.
Moral Event Horizon: In-Universe. The massacre of the Mage's Guild of Danalee by Guild elders causes a full-scale revolt among the guild, leading to its collapse.
Tear Jerker: When Sergeant Kali dies brutally and suddenly in the Battle of Dorcastle, Mari goes into a shocked rage. Later, it's all she can think about.
What Do You Mean, It's for Kids?: It's a YA series, but that doesn't stop the battle scenes from being brutal and full of deaths written from the perspective of a military veteran author. Nor does it stop one of the Great Guilds being full of rapists.
