Robin and his partner Shadow are desert wanderers in the post-apocalyptic American Southwest. Despite their efforts to help locals, they are regarded with suspicion for Robin's connection to the monstrous fireworms and his ability to dowse for water, and most people know Robin only as Daystar.
Daystar and Shadow contains examples of:
- Abandon the Disabled: This was Robin and presumably Shadow's hometowns' policies for autistic children. Part of it is because life is difficult for everyone and children who can't work are a liability, but the New Christian Church stresses the necessity of killing autistic children to a degree that often confuses outsiders.
- After the End: A devastating event called the Holocaust happened about a thousand years ago. Now much of America is uninhabitable wasteland.
- Air-Vent Passageway: A monkey crawls through a vent in the New Christians' stronghold to free Robin when he's tied up.
- Amnesiac Hero: Robin can remember virtually nothing before the age of about eleven, except for hazy memories of his parents abandoning him in the desert as a three-year-old for being "artistic."
- Attempted Rape: A few days after Robin and Shadow meet, Robin leaves her alone at the campsite and comes back to find three men trying to rape her, even though she's about ten years old at the time. Robin, who's a teenager at this point, kills two of the men and chases the third off. He and Shadow have to leave the area after that.
- Battle in the Center of the Mind: Robin's fight against a Mind Probe involves hiding in a cave inside his mind and trying to block it off with bricks, while the probe is represented by fire. Robin and the probe attack each other with various weapons and animals, with Robin receiving psychic assistance from Shadow.
- Death by Despair: Robin's mother Marge withered away and died after being forced to abandon him in the desert, saying life had no meaning for her. His father worked himself to death over the loss of Marge, Robin, and their other son Gregory, who was killed by a fireworm.
- Disability Superpower: All autistics have telepathy.
- Domestic Abuse: Robin's father hits his mother for disobeying or arguing with him.
- Dowsing Device: Robin uses a rod, even though he doesn't need one, because a physical object makes dowsing look less supernatural and more scientific.
- Eyes Always Averted: Robin and Shadow rarely make eye contact, either with each other or with other people. Robin eventually learns from Annette that this is a symptom of autism.
- Fluffy Tamer: For reasons Robin doesn't understand, the fireworms won't hurt him and sometimes even protect him. Once a small fireworm presses against his leg and purrs like a cat.
- Full-Frontal Assault: Robin and Shadow are surprised by enemy soldiers right after having sex. Robin has Shadow run to safety with their clothes while he fires back naked.
- Goal-Oriented Evolution: Autism is the next stage in human evolution, as it comes with abilities such as telepathy and water dowsing.
- Good Cop/Bad Cop: Robin and Willy do this on a priest. Willy uses the Jack Bauer Interrogation Technique until he breaks, then leaves him alone with Robin for a gentler interrogation.
- Hates Being Touched: As a young child, Robin struggles to escape every time his mother picks him up. As adults, Shadow flinches from him and only touches him when necessary, such as when helping each other over rough terrain.
- Hostile Terraforming: Turns out to be the motive of both the Hemn and the Others. The Others want to turn the world into a desert, kill most humans, and infect everyone else with a parasite that turns them into plants the Others can eat. The Hemn want to cause runaway Global Warming to create a hot, humid ocean planet where their civilization can flourish.
- I Did What I Had to Do: When Robin feels guilty for interrogating some priests, then killing them for knowing too much and burning the church down, Shadow reminds him that it was necessary.
- Left for Dead: Robin's father leaves him in the desert to be killed by fireworms.
- Night-Vision Goggles: The sentries outside the New Christians' citadel wear helmets with infrared goggles at night.
- Obfuscating Insanity: Diego pretends to be autistic in the hopes of being captured by the New Christians so Robin can follow them and find out where they've taken Diego's sister and Shadow.
- Only Known by Their Nickname: Robin doesn't even know Shadow's real name. She got her nickname from a fruit vendor in Hermosillo who said, "She is like a sombra, that girl, to you."
- Parental Substitute: The Professor, an old traveling Storyteller with a team of trained monkeys, found Robin playing in the desert shortly after his memory awoke and raised him for the next five or six years.
- Path of Inspiration: The New Christians seem like an extremely powerful organization of fundamentalists who want to keep their society as technologically simple as possible. In fact, their leaders are infected with mind control parasites from the Others, who have programmed them to do their bidding.
- Post-Victory Collapse: Robin faints after frying the mind probe.
- Potty Failure: Robin loses control of his bladder while fighting the mind probe. He clings to the feeling of wetness, which gives him a hold on the outside world.
- Power-Strain Blackout: Under Shadow's leadership, a group of prisoners with barely-developed psychic powers try to put their four guards to sleep. They have little success, and by the end most of them are nonfunctional from exhaustion.
- Precision F-Strike: While talking about Robin's relationship with fireworms, Shadow asks him, "Then what is the goddamn connection?" Robin is startled, as he's never heard her use profanity before, which helps emphasize her point.
- Ray Gun: Robin is shocked to see that Shadow's kidnappers all have lasers, as lasers are extremely rare.
- Seeing Through Another's Eyes: Using all his mental ability, Robin can get a smoky view of what Shadow is looking at.
- Starfish Aliens: The Hemn, aka the Monitors, are a Hive Mind that resemble sea anemones, live in pools of a mysterious solution to avoid being killed by Earth's atmosphere, communicate telepathically via a mixture of ideas and images that coalesce into words, and refer to themselves as "I/We."
- Telepathy: Robin and Shadow communicate primarily by telepathically feeling each other's emotions. Robin can do it with dolphins, too. It turns out every autistic has it, although most aren't nearly as good at using it as Shadow and Robin.
- Their First Time: Robin and Shadow have awkward, unsatisfying sex while hiding above the entrance to the New Christian stronghold. Afterward, Shadow is distant, which Robin eventually realizes is because he only used his body when she wanted him to use his mind as well.
- Throw-Away Guns: Shadow tosses her laser aside when it runs out of power.
- Troubled Fetal Position: Shadow spends a lot of time in one during the early days after Robin takes her in.
- Working Out Their Emotions: Robin deals with what he calls brain-burners, when his mind races out of control and he starts to retreat inside himself, by sprinting a few miles until he's burned off the excess energy. He teaches Shadow to do the same.
