A Lesson Learned Too Well: Snape tells Harry he should be careful and not trust Dumbledore because whether good intentions or not Dumbledore is responsible for Harry getting placed in an abusive home. Harry takes his advice and starts to fear Dumbledore more than he does Voldemort to Snape's horror.
Accidental Misnaming: Harry calls Voldemort Vol-au-Vent and Voldesnort. Snape decides to stop trying to correct Harry after a while.
Accomplice by Inaction: Snape and Harry come to fear Dumbledore when they both realize he didn't check up on Harry, enabling the Dursley's abuse or when Dumbledore didn't insist that Sirius get a trial.
Age-Appropriate Angst: Lampshaded by Hermione and Ron when Harry is moping about not spending time with Snape. To avoid embarrassing him, they say it's only because he's not used to Snape the way they are used to their parents.
Bad Boss: Snape shows signs of this in regards to Lucius Malfoy. A simple assignment from the former? Overthrow the government in the next few months. Backfires when the latter tries to gain some recognition.
Dark Humor : Mad-eye, as seen when he dubs the partially liquified Pettigrew "Pettigoo".
Dark Is Not Evil/Light Is Not Good: Being from Slytherin doesn't automatically make you a Death Eater and being from any of the other three Houses doesn't mean you can't be one as we find out from several Ravenclaws.
Dirty Coward: Deconstructed. Slytherins encourage pragmatism and bringing back-up to a fight but anyone who totally abandons one's House and those protected by said House is considered the lowest of the low, Slytherin or not.
The Dreaded: Hermione becomes this after Harry's ambush. While breaking the wand of a fallen foe was considered "hardcore", her explanation of Muggle dentistry gave her the top spot for the "not mess with" list in the entire school.
Dumbledore became this for Harry for more than half of the fic.
Fantastic Racism: Played straight with the Death Eaters obviously and with Umbridge who calls Jones an island person who practices hoo doo despite the fact the girl was born in Brighton.
Fearless Fool: Deconstructed with Harry who lacks a sense of self-defense (and of self-preservation) thanks to his upbringing, allowing him to put himself in danger without a thought, much to Snape's annoyance and horror.
Fix Fic: One of the best written in the entire Potter Fandom. It avoids Mary Sues, superpowered versions, wangst and bashing and is so cutesy and epic that it would give you both diabetes and testosterone poison just by reading it.
Hoist by His Own Petard: Thanks to Snape's past misdeeds, it allow Umbridge to act scott free against the students of Howgarts, especially against Harry. Needless to say, McGonagall was grimly amused by Snape's cries of unfairness and abuse.
Honorary Uncle: Ron and Percy called Snape "Uncle Sev", much to his mortification. And Harry calls McGonagall "Auntie Min" later on.
Humiliation Conga: Fudge gets one of these, starting with his most trusted advisor unfurling a banner that reads, "FUDGE IS AN IDIOT."
Hypocritical Heartwarming: It doesn't matter what Snape may call Harry or how he acts with him, if you dare to insult, abuse or bully him in any way he will rip out your own intestine and beat you with them.
Insane Troll Logic: Snape can literally count how far the IQ of his fellow teachers drops any time somebody says "Quidditch".
As far Snape is concerned, this is how that brat's mind works all the time.
Imagine Spot: When things get too absurd, Snape mentally pens, "Dear (magazine's advice column/Voldemort), I am currently (dealing with playing daddy to the Boy Who Lived). Would (snarky/overkill reaction) be within the norm? Is it considered poor form to cut my own throat rather than suffer through such an excruciating evening?"
Kick the Son of a Bitch: What both Snape and McGonagall do to Dolores and Fudge after they try to attack Harry. While Snape managed to personally destroy Fudge's career, McGonagall takes the cake by Transfiguring and devouring Dolores alive.
Odd Friendship: Snape strikes one up with McGonagall, Sirius, Lupin and Molly Weasley. Also Hermione with Jones and Ron with Draco.
Oh, Crap: The two Death Eaters holding down Snape consider changing career paths when they see Harry arise from being Avada-ed.
Papa Wolf: No matter how much Snape denies it, he would go to any length, break any rule, face the Dark Lord and Dumbledore himself without hesitation if it mean Harry's protection. Soon enough most of the Wizarding World learned not to mess with Harry.
Lucius Malfoy is a more chilly, stern type.
Likewise with Dumbledore. He nearly hunted down Umbridge when he found out she used a Blood Quill on Harry. Also in the prequel, his casual warning to Snape if he should ever harm a student again.
Serious Business: Quidditch, to Snape's detriment. From forgetting that a student nearly killed himself in a broom to nearly starting a brawl in the great hall by the teachers, Quidditch certainly brings out the best and the worst of wizards.
Stern Teacher: Snape ends up being this, while trying to be a Sadist Teacher. Most of his punishments are actually helpful, as Harry frequently points out. Snape constantly blames Harry and his friends for ruining his reputation.
Surrounded by Idiots: When you get to know the point of view of Snape for all the decisions around Hogwarts, especially Potter, you can't not only sympathize but wonder how Snape hasn't just snapped already.
Too Dumb to Live: Umbridge's utter lack of self preservation when dealing with an enraged Snape and McGonagall during her "Potter Should Be Silenced" spiel ends poorly. Even Jones admits to being frightened of an angry McGonagall.
Ugly Guy, Hot Wife: While Percy is not ugly, he is defined as plain while Jones is often described as a very beautiful, willowy... and absolutely scary witch. Like a "saner, controlled version of Bellatrix Lestrange".
Villainous Rescue: Slytherin, as far as Hogwarts is concerned. But say what you will about the house, when one of their "Firsties" was in trouble, literally the entire House was moved to battle in seconds. As Harry's attackers learned the hard way.