Abusive Parents: Of all sorts. A particularly favoured type is the parent of the Littlest Cancer Patient / Ill Girl who considers themselves an exemplary parent because of their many sacrifices for their child... but completely fails to notice that they neglect (and, in My Sister's Keeper, exploit) the healthy sibling so badly that it borders on or becomes abuse.
Can't Get Away with Nuthin' : Theo, in House Rules. As a child, his mother promises him that they'll go to the cinema, a rare treat for Theo, who's constantly passed over in favour of keeping Jacob's "meltdowns" to a minimum. He's excited when the day of the trip arrives...only for Jacob to find out that he's out of books, and is threatening to throw a fit if he doesn't get new ones. They end up at the library instead of the cinema. On realising that his mother hasn't even noticed how badly she's disappointed her younger son (again), the usually well-behaved Theo decides to throw a tantrum in the middle of the library. Then his mother starts screaming and crying herself, an event that shocks Theo and leaves him feeling guilty years later.
Willow is portrayed as wise (almost saintly) beyond her years and possibly more sensible than her Knight Templar mother. The one time she actually acts her age, it costs her dearly: out of childish curiosity and fascination for the forbidden, she walks on to the ice-covered pond of her home. The ice shatters and Willow drowns.
The Caretaker: Emma, of her autistic son Jacob, in House Rules. Sarah of cancer-struck daughter Kate in My Sister's Keeper. Charlotte of daughter Willow, who has brittle bone disease, in Handle with Care. Note that both Sarah and Charlotte have husbands, but they tend to get shoved to the side thanks to their wives' Knight Templar attitudes. Theo, Jacob's brother, is resigned to the fact that when their mother dies, the caretaker role will default to him.
Interestingly, all three of the above are the narcissistic variants of The Caretaker. A good example is Emma from House Rules. What makes her snap at Jacob isn't the various indignities, injustices and serious injuries visited on Theo, her other son (including one serious incident which she has totally forgotten), or public tantrums, or injured classmates. It's when Jacob doesn't get her a present for her birthday, and later when Jacob points out, correctly, that she should not be having a romantic relationship with his lawyer. Even though any moron would realise why any child would be upset and angry at finding their mother kissing their lawyer while they are on trial (for murder, no less), never mind an autistic child, this is when she finally slaps him. Apparently, Jacob can mess up Theo's life and it's fine, but if Emma decides that she wants something and Jacob interferes, it's a different story.
Disappeared Dad: Several, a few examples being Zoe's father in Sing You Home and Josie's father in Nineteen Minutes.
Double Meaning Title: Several; for example, Change Of Heart referring both to the heart transplant and the back-and-forth as several characters try to weigh up the emotional dilemmas.
Easily Forgiven: In Harvesting The Heart, Paige O'Toole leaves her husband Nicholas for 3 months, then stalks him for a month or two, but Nicholas still takes her back (possibly; the ending leaves some room for interpretation).
You could argue that Charlotte's family forgives her rather easily in Handle with Care, given that she bulldozed the life of everyone within a three-mile radius of her. Laser-Guided Karma gets her in a particularly twisted way, however.
In Plain Truth, after winning Katie's case, lawyer Ellie lets it slide when she finds out Katie's mother either committed infanticide or tampered with the scene of the death so that it was ambiguous what really happened, risking Katie's imprisonment for the murder.
Flower Motifs: Mercy uses these time to time; unsurprising considering one of the main characters owns a flower shop.
Good Girls Avoid Abortion: Averted in Harvesting the Heart. Paige O'Toole gets pregnant when she is 17 and aborts the baby. When she meets Nicholas and marries him she feels guilty when they first have sex because he believes her to be a virgin and she hasn't corrected him. Later, after leaving him to find her mother she confesses to him tearfully that she had an abortion. He, of course, is angry.
Subverted in Nineteen Minutes with Josie. She finds out that she is pregnant with her boyfriend's baby, but doesn't want to get an abortion done in a clinic, because that would involve telling her mother. Instead, she manually induces a miscarriage.
The Pact: Emily gets pregnant with Chris' baby, and goes to have it aborted. However, the abortion is stopped, not because Emily has a change of heart, but because she freaked out when a male doctor started the procedure and says something to her that evokes her earlier sexual molestation. This causes her to spiral even further into depression, and eventually sets the plot of the book in motion.
Happily Married: Often the main couple will start out this way, but whether or not they stay that way goes up in the air.
Hot for Student: Laura Stone is with one of her students the night her daughter is date raped in The Tenth Circle.
In Salem Falls, the inverse appears with a student crushing on her teacher. The teacher in question is accused and even convicted of having had an affair with her, though nothing actually eventuated.
Ill Girl: Kate from My Sister's Keeper, Willow from Handle With Care and Claire from Change of Heart. Faith from Keeping Faith has moments like this as well, when she is hospitalized due to her apparent stigmata.
Informed Ability: The father's "ambitious" and "brilliant" comics in The Tenth Circle.
Insufferable Genius: Jacob in House Rules, even if his area of genius is limited. It's a trait of his autism. He openly states that his brother isn't as smart as him, and sees his lack of empathy as "the next step in evolution: I cannot take away your sadness, so why should I acknowledge it?"
Isolation Despondency: In Nineteen Minutes, Peter is forbidden to contact Josie Cormier after they're found playing with guns.
Karma Houdini: In Perfect Match, Nina gets away with murdering Father Szyszynski, the man accused of molesting her son, and Caleb gets away with murdering Father Gwynne, the man who actually did it.
Lampshade Hanging: Sean and Charlotte have a very theatrical reconciliation in the middle of the courtroom in Handle with Care. Amelia bitterly notes how contrived the scenario was, suspecting the judge of setting it up.
Littlest Cancer Patient: In My Sister's Keeper, Kate, who has had cancer since the age of 4, in her mother Sara's flashbacks and in Handle with Care, Willow, who suffers from osteogenesis imperfecta, or 'glass bone disease'.
Living Emotional Crutch: Jesse lampshades Anna's role in the family as this, in My Sister's Keeper. Charlotte and Sarah see themselves as their ill daughters' emotional crutches, but in reality it's the other way around (they define themselves by their child's illness, and their role as mother/martyr). Theo is a more practical emotional crutch to his older brother Jacob, since teachers frequently call in Theo to deal with Jacob's autism-related "meltdowns".
Maybe Magic, Maybe Mundane: Apparently messianic acts done by/happened to Shay Bourne in Change of Heart. Some of them are explained away as being definitely mundane, but it remains unclear whether all are. The ending involves Claire performing a similarly messianic act after the heart transplant.
No Ending: Partially. In House Rules and Handle with Care, novels that feature a special needs child and their emotionally-neglected sibling, the special needs child gets closure ( even if, as in Handle With Care, it's pretty grim closure) while the sibling remains something of an untied plot thread.
No Sympathy: Many of her characters (especially the mothers) are completely obsessed with the feelings and suffering of one specific person, but oblivious to the pain of everyone else around them — even within their own families.
Jacob's autism causes him to be viewed as a more obviously un-empathetic character — it's why he's suspected of murder in the first place.
Only Sane Man: The fathers in My Sister's Keeper and Handle with Care, while not without their issues, come across as this. For most of the novel, they're the only ones to see the bigger picture and both sides of the argument... at least until the last few chapters. Brian loses his nerve on the stand and confesses that he wants Anna to give Kate a kidney, after spending most of the book being one of Anna's few allies. Sean has a very staged reunion with his wife (set up by the judge) that sees him rejoining her "side" of the trial). Anna, one of the few people who know what's actually going on in My Sister's Keeper and the beleaguered Piper Reece in Handle with Care eventually turn out to be the real "sane (wo)men."
As well as in Vanishing Acts when Delia finds out her mother's lover may have raped her, thus provoking her father to kidnap her.
Ripped from the Headlines: My Sister's Keeper was based on a real life story of a family who had a child(unintentionally) that was an exact match for their daughter who had cancer. Many of her other books seem to be ripped from the headlines, but aren't.
Shoot the Shaggy Dog: Anna's battle for medical emancipation in My Sister's Keeper is proven pointless when she dies in a car accident and both her kidneys are harvested for her older sister.
Handle With Care plays out almost exactly like this. Well, I betrayed my best friend and ruined her reputation, my other daughter is now suffering from bulimia and cuts herself often due to the neglect...but at least I still have this check that will ensure that Willow will be able to live an almost-normal life! Oh wait, she drowned, which makes this check pretty much worthless. Damn.
Strictly Formula: All her books have the same (general) formula: People (usually centering on the woman) living a normal life (in some New England town), something big happens/happened to them (i.e. husband is cheating, child is arrested) and there ends up being a court case either involving family members (i.e a family member committed a crime) or involving family members suing each other. Usually the court case involves children or teens. Expect one child to be severely ill and wiser than their years. The parents will/already did forget about the other child, if there is one. It is often a Tear Jerker, but is successful because of that (the judge/jury feels sorry for the defendant). Usually there is a Shocking Swerve near the end, and somebody dies. Glaring examples include My Sister's Keeper and Handle with Care, which has been criticized for being nearly identical to My Sister's Keeper.
In Lone Wolf, the real reason Edward left home was his walking in on his father sleeping with a college student, apparently not for the first time.
The sub-plot of Mercy is about Cam cheating on his wife Addie with Mia, who was Addie's new employee at her flower shop.
The plot of Keeping Faith kicks off when Mariah and Colin divorce after Mariah and Faith walk in on Colin in the shower with his mistress. It is later revealed that this was not Colin's first affair, nor even the first time he was caught.
In The Tenth Circle, Laura is having an affair with one of her students, and was with him the night her daughter was date-raped.
In The Storyteller, the protagonist Sage is having an ongoing affair with Adam, a married man.