These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Mortal Engines
Crowning Moment of Heartwarming: In A Darkling Plain, the scenes where Fishcake and Anna find Sathya's hermitage in the mountains, and start acting like a family... Especially the scene where Anna carves a toy horse for Fishcake, and he acts like it's the most beautiful thing he's ever seen. Sniff.
Les Yay: Plenty between Sathya and Anna Fang. Sathya created the Green Storm and revives Anna Fang because of this. Even the Stalkerized Anna goes back to Sathya. Confirmed by General Naga in the last book.
Too Cool to Live: Shrike and Anna Fang in the first book. In fact, Too Cool To Die as they're both resurrected in the sequels.
The Woobie: Throughout Mortal Engines, Katherine Valentine discovers that the city she calls her home is not as shiny as she thought, that most inhabitants don't consider her as one of them anyway, and that the person she trusted the most is a liar, a thief and a murderer. Add the death of anyone else whom she ever cared for and by the end of the book, she's become a Determinator to the point it's heartwrenching.
Tom and Hester also count as one too.
Valentine might be a Jerkass Woobie; he did terrible things, but he wanted to make a better world for Katherine, and this backfired spectacularly.