Anji has become ill, while meanwhile the TARDIS has started malfunctioning. After they land on the planet Ceres Alpha to find medical care for Anji, Fitz becomes injured and the Doctor and Anji become embroiled in a mysterious case involving some eerie, telepathic children, who look alien despite being born to human mothers, and whom the MegaCorp attempting to terraform the planet is anxious to cover up.
Tropes present in Dark Progeny include:
- Big "NO!": The Doctor loses his composure significantly when Gaskill Tyran, the Villain of the Week, threatens to shoot Fitz.
- Black Eyes of Evil: The telepathic children, and Anji while under their influence. Subverted in that they're not as evil as they initially seem to be.
- Confronting Your Imposter: The Doctor's ruse of being some Doctor Domecque whom the folks on Ceres Alpha have been expecting to drop in to investigate the matter of the telepathic children works until the real Doctor Domecque shows up. Then he gets the shit beaten out of him.
- Convenient Misfire: Justified by the children's telekinetic abilities.
- Creepy Child: The titular "dark progeny". The Doctor finds them rather endearing, though, which diminishes the creepiness somewhat.
- Cuteness Proximity: The Doctor isn't scared of spooky, skinny, pale tots with giant black eyes. He thinks they're adorable.
- Disney Death: Fitz, although the Doctor is left thinking he's dead for much longer than the reader is, and therefore most of the emotional importance comes from the Doctor's reaction. Anji is seemingly killed off at one point too, although so casually it's hard to take it seriously.
- Driven to Suicide: Pryce, apparently due to some kind of feedback loop of hostility between himself and the telepathic children.
- Gaia's Lament: On Earth, things such as trees and birds are a thing of the past. The humans on Ceres Alpha are hoping to introduce plants and wildlife after they terraform the planet.
- Gaia's Vengeance: Lighter and Softer: The planet just wanted to have a nice chat, apparently.
- Hive Mind: The telepathic children. They seem to have some degree of individuality, but they share knowledge and memories.
- I Will Only Slow You Down: Fitz falls down and hurts his leg too badly to walk on it. He tells the Doctor to go on with Anji and leave him behind, which is unfortunately the Doctor's only sensible option.
- Love Makes You Dumb: Tyran attempts to interrogate the Doctor by pointing a gun at the assembled bystanders, to see which one of them the Doctor cares the most about. The Doctor doesn't even make the slightest attempt to bluff him when he points it at Fitz, nearly causing Fitz to actually get shot for real.
- Older Than They Look: Thanks to advances in medicine and plastic surgery, most of the characters introduced in this book look young or middle-aged despite being much older. Likewise, Anji is considered very young for being merely in her twenties.
- Scary Flashlight Face:Bains saw a grotesquely uplit face gazing at him from across the room, thick shadows in all the wrong places making the thing appear frighteningly horrific.
- Shout-Out: The Doctor gives the spooky kids names from Cats. They try to rename him Old Deuteronomy.
- Twisted Ankle: Poor, clumsy Fitz...
- Two Lines, No Waiting: ... who spends most of the book trying to find the Doctor, Anji, and/or the TARDIS.
- What Have We Ear?: The Doctor entertains the telepathic children by pulling a ping-pong ball from his mouth or behind their ears. He also does it a couple times seemingly in the hopes that it'll entertain random adults too.
- What Measure Is a Non-Human?: The Doctor is told about some dangerous "creatures", and is surprised when he meets one and finds out they're actually babies.
- Why Did It Have to Be Snakes?: Anji doesn't really do phobias, but she doesn't like rats much. She especially doesn't like being trapped in a maintenance elevator with rats the size of cats.
- You Are Number 6: The telepathic children have numbers rather than names, so the Doctor gives them names.
- Younger Than They Look: The telepathic children can walk and talk and seem to resemble toddlers, but are actually only two months old.
