Black Magic: In Dead Iron, Mae's magic twists to this and causes pain. She uses great care to use it only beneficially—keeping out vermin—and laboriously learned to undo curses and other dark bindings.
Blow You Away: In Dead Iron, Cedar's arrival at the mine is announced by dust devils that form without any wind.
Cue the Sun: In Dead Iron, the sun comes from behind the clouds just as Mae sets out to the Madder brothers'. She takes it as a good omen.
Dark and Troubled Past: In Dead Iron, Cedar's brother Wil dragged him west after the loss of his wife and children. Then they went on the wrong land and were cursed into werewolf form. Cedar came to find himself at the end of a bloody trail, and backtracked to find his brother's wolf corpse, its throat torn out by himself.
The Eyes Have It: In Dead Iron, a room of Strangework mantics is absolutely still, except for eyes following LeFel and Mr. Shunt.
A Friend in Need: In Dead Iron, when Rose is thrown out of the meeting where the Witch Hunt is started, she resolves that nothing can stop her from helping Mae.
Good Samaritan: Cedar goes to hunt down a lost child despite the treatment he gets in the town.
Insubstantial Ingredients: Played with in Dead Iron, Alun Maddox talks of spoons made of moonlight — and Cedar says his gun is made with pain.
Moses in the Bulrushes: In Dead Iron, Rose Small's backstory was being abandoned on the step of her adoptive parents' home.
Must Be Invited: In Dead Iron, Mae explicitly refuses permission to enter her home, though the effect appears to be more her spells than the refusal.
Our Werewolves Are Different: In Dead Iron, Cedar, under a curse, changes by the full moon and loses his mind, requiring him to chain himself. He pays quite dearly for a collar that lets him keep his right mind. Later we learn his brother Wil is still alive and also under a curse, but while Cedar only changes during the full moon, Wil is permanently a wolf, and fortunately, can control himself all the time when not actively bespelled by LeFel.
Power of Love: In Dead Iron, LeFel has to kill Jeb because otherwise his and Mae's love would protect her.
Rule of Three: In Dead Iron, LeFel tries to invoke this on Jeb Lindson — he shouldn't have to kill him more than three times.
Something About a Rose: In Cold Copper, Captain Hink had given Rose a wallpaper rose, folded paper and perfumed. She had kissed him — more than once — because of it.
Windows to the Soul: In Dead Iron, Wil's eyes are still copper even in wolf form. The precise color is not so significant as what it shows about Wil's ability to keep his human mind in wolf form.