Apparatus Infernum is a series of novels written by Ann Aguirre and Andres Aguirre (under the merged name A. A. Aguirre). The setting is Steampunk-slash-Fantasy, probably falling within the Gaslamp Fantasy genre. It focuses on a pair of police investigators, Janus Mikani and Celeste Ritsuko.
The two books released so far are:
- Bronze Gods
- Silver Mirrors
This series provides examples of:
- Altar Diplomacy: A long time before the main story, war between humans and Ferishers (the magical people who inhabited the islands before humans arrived) ended in a treaty that saw mass intermarriage between the ruling families of each side. Over the years, the magical ability so gained has gradually filtered into the general population, so it's not uncommon for people with no apparent connection to the nobility to have a bit of Ferisher ancestry (and therefore a bit of magic). One of the protagonists, Mikani, is such a person.
- Amicable Exes: Mikani and Saskia are not on completely relaxed terms, and have a few leftover complaints against each other (such as Saskia not letting go of the fact that Mikani once tried to arrest her). However, it's more exasperation than bitterness, and when they have to work together, they do reasonably well. (This is noted to be unusual for Mikani, whose numerous ex-girlfriends seldom end up on speaking terms with him.)
- Arranged Marriage: Ritsuko wasn't set up with one specific partner, but was given a list of suitable choices. As of the start of the series, she has just given up on the last of them, which is within her rights but has left her family Very Disappointed to the point of ostracism.
- Badass Bookworm: Ritsuko is notably on the academic side, especially compared to her partner Mikani, but that doesn't stop her from fighting.
- Da Chief: Gunwood, the protagonists' boss at the Criminal Investigation Division right down to effectively telling them to Turn in Your Badge. However, his frustration with the protagonists is not so much because they're indulging in Cowboy Cop behaviour as because he's under huge pressure from high up to produce a result soon. Behind the shouting, he's more of a "A Father to His Men" model.
- Lineage Comes from the Father: Society tends to believe this, which creates a plot-relevant blind spot that hinders the protagonists. They'd like to track down descendants of a certain noble House, but the official records only concern themselves with the patrilineal line and because that line came to an end, the House is considered extinct. In fact, if you count descent from women of the House in question who married into other Houses, descendants are still quite present just under other names.
- Looking for Love in All the Wrong Places: Mikani has a long list of ex-girlfriends, none of whom lasted very long and almost all of whom are now on bad terms with him. His developing relationship with Ritsuko is a break from the pattern, and is considerably more solid even though it hasn't actually gone nearly as far.
- Magitek: The setting makes extensive use of magic and technology in concert in particular, elementals (fire, air, etc) are harnessed to power steam-era technology like trains. This becomes directly relevant to the plot in the second book, when the elemental-based tech starts misbehaving and the protagonists have to find out why.
- Melting-Pot Nomenclature: All sorts of names co-exist in the setting, ranging from Scandinavian to Japanese. This reflects the diverse origins of the settlers from "our" world who stumbled on it.
- No Sparks: Ritsuko's reason for breaking up with the guy her family would have liked her to marry. Things were pleasant enough, but she realised that if that's all there was, both of them were just wasting their time.
- Reasonable Authority Figure:
- The Magnus commander in Silver Mirrors, within certain limits. He's arrogant, and is primarily concerned with advancing House Magnus interests (and himself with them), but he gives Mikani and Ritsuko a fair hearing despite having both the legal and military power to ignore them, and realises that the threat in question is serious enough to warrant direct action even though it could drag House Magnus into a war.
- Gunwood would probably like to be, but he's often under too much political pressure.
- Turn in Your Badge: In Bronze Gods, The powers that be want a quicker result than Mikani and Ritsuko are providing, and since Mikani isn't inclined to be taken off the case quietly, Gunwood orders him to take a few days off (upgraded to a week thanks to Mikani not knowing when to keep quiet). They aren't made to literally hand over their badges, but it plays out much the same.
- Unresolved Sexual Tension: Strong between the two protagonists, Mikani and Ritsuko. Their attraction is obvious, but there's no way that either of them are going to admit it, or even talk directly about it.
- Working with the Ex: Saskia Braelan, one of Mikani's numerous ex-girlfriends, has a minor role in the first book and a major one in the second mostly because Mikani needs to ask (and then repay) favours. Their relationship is generally pretty amicable, so the fact that they have to work together doesn't pose too much of a problem to them, but it does cause some anxiety for Ritsuko, with whom Mikani has a lot of Unresolved Sexual Tension.