''Catalyst'' is a 2002 novel by Laurie Halse Anderson. The story takes place in the same universe as Halse's acclaimed novel {{Speak}}, a year after the events of that novel, and focuses on senior Kate Malone as she makes plans for college.

Kate is a preacher's daughter who excels in chemistry and is a star track athlete, with her sights dead-set on getting into the Massachussetts Institute of Technology once she graduates from Merryweather High School. She's so determined, in fact, that it's the only college she's applied to. Her getting rejected is just the tip of the iceberg, however, as soon afterwards a fire renders her neighbors - her abrasive school nemesis Teri Litch, Teri's mentally unstable mother, and her adorable toddler brother Mikey - homeless, and Kate's father arranges for Teri and Mikey to move in with his family. Kate must now struggle to deal with her rejection from MIT and a less-than-pleasant new roommate, all while maintaining her sanity.
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! Provides the following examples:


* AbusiveParents: Teri's father turns out to have been one.
* TheAce: Kate - stellar track athlete, budding chemist, mathematics expert - in her eyes, a perfect candidate for MIT.
* BreakTheHaughty: The whole story is a seemingly endless one for Kate.
* [[spoiler: ChildByRape: Mikey, who is both Teri's brother ''and'' her son.]]
** [[spoiler: ParentalIncest]]
* CloudCuckoolander: Betty, an elderly neighbor of the Malones and the one to take in Mrs. Litch after the fire, claims she can sometimes see {{Jesus}} in her television. Then there's Teri's mother, a less comedic example.
* TheCameo: Melinda Sordino, the protagonist of {{Speak}}, makes a brief one - just long enough for the audience to learn [[spoiler:how much better she's doing]]. Kate can't seem to remember her last name, instead calling her "Melinda Something" in the narration.
* ChildrenAreInnocent: Two-year-old Mikey Litch. The biggest problem he ever ends up causing is an exceptionally filthy diaper.
* DeadPersonImpersonation: Kate pretends to be her deceased mother when she calls MIT's enrollment office to find out why she was rejected.
* DisappearedDad: Teri's father is not in the picture, having died in jail after attacking his wife with a baseball bat [[spoiler: and impregnating his daughter.]]
* HeroicBSOD: [[spoiler: ''Everyone'' goes through this in varying degrees after Mikey's death, but particularly Teri.]]
* [[IllGirl Ill Boy:]] Kate's brother, Toby, is implied to have been plagued with respiratory problems since he was very young.
* [[spoiler:InfantImmortality: ''Painfully'' averted.]]
* TheMourningAfter: Jack Malone, who once told someone that he buried his heart along with [[TheLostLenore his wife.]]
* NoNameGiven: Teri's mother is only ever called Mrs. Litch.
* PromotionToParent: Teri has largely taken on the role of caring for Mikey, seeing as Mrs. Litch is...not entirely there. [[spoiler: Ultimately averted - Teri ''is'' the parent.]]
* StickyFingers: Teri, who unabashedly steals (and wears) Kate's watch, and later the necklace her boyfriend Mitch gave her.