Percy is having a great 13th birthday until the old-man knocks on his door. Now, Percy's life is a double-mistake, because gods aren't supposed to have wizard children. Zeus is furious, and banishes him from the country, leaving Percy with no choice but to attend Hogwarts. But, maybe a magic school is his chance to finally have a safe, monster-free, normal school year.
Percy Jackson and the Horror Within is a Percy Jackson and the Olympians and Harry Potter crossover by Procrastinating4237
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It can be read here.
Percy Jackson and the Horror Within contains examples of:
- Animal Talk: Besides being able to talk with sea creatures and equines as usual due to being a son of Poseidon, Percy is also a Parselmouth and can talk with snakes due to being Voldemort's grandson and so a descendant of Salazar Slytherin.
- Blackmail: So Lockhart stops to make him and other students who don't want to imitate the beasts that he supposedly bested, Annabeth gives Percy the idea of pranking the faker and threatening him in secret to stop doing it unless they volunteered or there will be more from there.
- Boarding School: Percy is not new in going to schools away from his home, but here it's taken to another level with Zeus making him go to Hogwarts instead of Ilvermorny to learn magic as a means to punish Poseidon.
- Bully Hunter: As usual this is Percy to a T, the only thing that stops him from going to get in the middle of Draco taunting Harry and Ron is Lockhart appearing and when the bully began to harass his friends from Hufflepuff in the library alongside Crabbe and Goyle he proceeded to embarrass him in public.
- Bullying a Dragon: After the embarrasment mentioned above, Draco threatens Percy saying that he will tell his father about this, who is one of the governors of the school, and he would expel him. But when Ernie mentions his worries the demigod just shrugs it off and laughs by imagining the stuck-up arrogant mortal trying to mess with Zeus's orders.
- And of course there is the fact that Draco Malfoy trying to intimidate the demigod-wizard son of Poseidon, who saved the world that past summer after fighting and winning against the Greek god of war and achieving many other acomplishments, already makes him worthy of this trope.
- The Champion: Hecate wants Percy to be her champion since a demigod wizard is the only way that she has to influence the Wizarding World, and hopes that the son of Poseidon will be able to change it since it has become stale as of late (as well as vulnerable for the dangers that will come in the future) and in the process vanish the restriction of the gods to not meddle there too.
- Child by Rape: In this story it turns out that Sally Jackson is the illegitimate daughter of Voldemort and a descendant of Helga Hufflepuff named Elizabeth Smith, it's heavily implied that the Dark Lord forced her into it.
- Child of Forbidden Love: Not only did Poseidon break his oath to not sire anymore demigod children by having Percy, but he also had him with Sally (who is a squib in this story) that passed magic to her son which was also forbidden after all of what happened with Grindelwald in the past.
- Curb-Stomp Battle: Draco, Crabbe and Goyle try to ambush Percy in the bathroom, but the demigod completely humiliates them to the point that Malfoy doesn't tell anything to Snape when he asks, with the hope of giving a detention to the son of Poseidon, so their embarrasing defeat doesn't become public to the rest of the school.
- Declaration of Protection: Dumbledore suspects that Percy and Sally are being threatened by the family of Percy's father (who sound all shady), so he gives the mom a mirror from a pair which are connected to one another, so she can ask him for help if she ever needs it. Percy is understandably very relieved by this.
- Dysfunctional Family: Annabeth suggests Percy to tell in the Wizarding World that his father's family has some serious issues and that's why he lived with his mom and decided to attend Hogwarts to stay away from all of that. His descriptions make people think that Percy is connected to the supernatural mob and he goes along with it for fun.
- Early-Bird Cameo: In chapter 3 before using a portkey to go to London, Percy sees who appears to be Tyson peering at him from inside a refrigeration box.
- Entertainingly Wrong: When Ollivander is talking about Percy's heritage, Percy knows he is talking about Poseidon, while Dumbledore assumes he means Voldemort.
- Fan of Underdog: The reason as to why Percy chooses to be sorted into Hufflepuff is because he looks up to the values of the House in particular and it's filled with underdogs which he has experience for being the nicest and make him feel like he belongs.
- Forbidden Love: After Grindelwald was stopped from revealing the gods and the truth of the world to everyone, the Olympians decided to stop interacting with the Wizarding World or having children with wizards and witches to prevent something similar from happening in the future. However in this story Sally is a squib who was adopted by muggle parents after she was born and so neither Poseidon or her knew of her heritage when they started a relationship and had Percy who inherited magic as a result, which in this story makes their already forbidden love from the oath of the "Big Three" have another layer.
- Freudian Excuse Is No Excuse: When Percy asks Snape why he bullies Neville during his detention with him, Snape's reaction clues Percy in that Snape had been bullied himself, but Percy notes that that isn't an excuse for his behavior and that Snape should be stopping bullies instead of being one himself.
- Goggles Do Something Unusual: Hecate gives to Percy special glasses the first night that he spends at Hogwarts to help him with his dyslexia by being able to translate English into Ancient Greek.
- Heart Is an Awesome Power: Percy takes Cedric's speech about how Hufflepuff's strength lies in teamwork to heart, and helps fix a fellow Hufflepuff's potion, while getting in a jab at Snape.
- Heroic Bastard: On Percy's godly side, but he is also the illegitimate grandson of Voldemort, and a descendent of Helga Hufflepuff the Dark Lord raped.
- Hiding Your Heritage:
- Percy has to hide to the Wizarding World, and especially Dumbledore, the fact that he's a demigod son of Poseidon as well as the Olympians and all the myths of Greek mythology being actually real, as well as hide the Wizarding World to his companions at Camp Half-Blood with the exception of Annabeth and Grover.
- Dumbledore admits that Percy's grandmother was a Smith family member, which is a prominent Pureblood family in Great Britain but warns him that they could not be accepting of Percy as a bastard. After his first meeting with his cousin, Zacharias Smith, and seeing his snobbish behavior, Percy concludes that Dumbledore is probably right, and decides to keep it as a secret.
- At the same time Dumbledore is hiding to Sally, Percy and the rest of the Wizarding World that both of them are related to Voldemort with him being the former's blood father and the latter's maternal grandfather in particular.
- It's revealed in the story that Grindelwald was actually a son of Apollo who wanted to reveal the secrets of the gods to the world but never told Dumbledore about any of that in spite of being "intimate," the majority thinks that is because he didn't trust him but Chiron likes to think that it was because the tyrant wanted to protect Albus from the Olympians.
- Hybrid Power: In this story not only is Percy a demigod son of Poseidon and has his usual abilities, but he's also a wizard and can use magic as well as speak Parseltongue because Sally turns out to be a squib daughter of Voldemort and Elizabeth Smith (a descendant of Helga Hufflepuff) who was adopted by muggle parents. This is unfortunately dangerous for Percy, as such demigod-wizard hybrids have forbidden after the a certain son of Apollo named Grindelwald (yes, that Grindelwald). So Percy's birth is twice as illegal (even if Poseidon was unaware of Sally's heritage) and dangerous.
- It's also explained that both of his powers, while still separate from one another, can complement each other and is a reason as to why Percy develops his demigod abilities at such a fast pace and makes him particularly powerful even for a son of Poseidon.
- If Only You Knew: Lawrence, the man who was tracking down Sally since she was moved to the US after her birth, tells Dumbledore how he hopes that all of what happened between June 9th and 21st happened because of Percy's father instead of the Dark Lord because no matter what crazy things he could've done it just can't be worse than anything related with Voldemort, to which Dumbledore agrees. Of course, knowing Percy's dad is the Greek god of the sea, and how the world was about to be destroyed because of a war breaking out among the Olympians, makes it pretty funny in hindsight.
- I Resemble That Remark!: When Percy notes that the portraits in Dumbledore's are only pretending to sleep to Harry, he says that one in particular does a snort every time he peeks open his eye. Said portrait stops pretending to claim that his fake sleeping is very convincing.
- Last Request: Elizabeth Smith, Sally's biological mother in this story, asked Jim and Estelle Jackson to take her newborn daughter and raise her as their own as a last wish.
- Mama Bear: While the details of her escape are unknown, Elizabeth Smith still successfully escaped the Death Eaters that held her captive out of love for her child despite knowing the risk, a child by rape at that, and her dying wish was to ensure that her baby was safe and as far away from Voldemort and his followers as possible. Whatever else, she loved Sally more than her own life.
- Mutual Masquerade: Thanks in part due to Grindelwald's power and actions as a son of Apollo and wizard, the gods have kept their existence secret from wizardkind besides the rule on not siring demigods with wizarding blood, and the Statute means that most ordinary demigods are unaware of the wizarding world as well.
- Not Me This Time: Percy is upset when Dumbledore singles him out for questioning after the attack on Mrs. Norris, despite him having nothing to do with it. He is unaware though that he is Voldemort's grandson, and thus an obvious suspect for the 'Heir of Slytherin.' He suspicions continue when it happens again with Sir-Nearly-Headless-Nick, although this time Dumbledore is able to deflect it more.
- Piggybacking on Hitler: Chiron tells Percy that Grindelwald, a son of Apollo in this story, was actually secretly allied with the Axis powers that were being led by the sons of Hades, with him and his army conquering the Wizarding World while the Axis did it with the mortal one.
- They Would Cut You Up: In this story Grindelwald was actually a demigod wizard son of Apollo and had both demigods and other demigod wizards in his army, Chiron informs to Percy that after witnessing how effective this unstoppable warriors of his were over the years some Dark Wizards have done terrible experiments to mortals thinking that Gellert magically enhanced them to create the super soldiers.
- Trophy Child: What Dumbledore speculates Sally was originally supposed to be. He believes "Voldemort attempted to become immortalized through an offspring descendant from the Hogwarts founders." However he also feels Voldemort now regrets the perceived weakness in doing so, and likely would kill such a child now.
- You Are Better Than You Think You Are: When Percy talks with Cedric and explains that he doesn't see why the popular older student would want to befriend him with how "uncool" he is, Cedric makes a point to note that the demigod underestimates himself.
