Something Wicked, by Riley Anna, is a Spring Awakening and Harry Potter Crossover Fan Fiction.
It's posted on Archive of Our Own  and Fanfiction.net 
Something Wicked contains examples of:
- Abusive Parents
- Martha's father (and, it's hinted, Ilse's), much like their Spring Awakening counterparts, are physically and sexually abusive toward the girls.
- Moritz's parents seem to have shades of this, since in "sky-blue stockings" Moritz tells Mrs. Gabor he much prefers spending the summer with Melchior. "Being home was not so bad, necessarily, but it was just...not so good."
- Adaptational Villainy: Professor Merrythought in Potter canon has no traits to speak of. Merrythought in Something Wicked is a racist Sadist Teacher who happily bullies her Deaf and Muggle-born students.
- Adjusting Your Glasses: Georg does this before "politely" swearing at Hänschen.
- After-Action Patch-Up: Martha for Moritz at the beginning of "this brave new you that you are."
He knew little of Healing magic, but sticking fingers into the wound until he had to bite his hand to stifle his cries didnt seem right.
- All Girls Want Bad Boys: The Ravenclaw girls on the Hogwarts Express who "sigh longingly at the sight of Melchior or Hänschen or both."
- all lowercase letters: Chapter titles are styled this way.
- Aloof Big Brother: Hänschen to Thea and Melitta.
- Alternate Universe Fic: Spring Awakening, but at Hogwarts.
- Ascended Extra: Most of the kids who aren't Melchior, Moritz, or Wendla get more stage time and character development than they do in Spring Awakening
- Especially true for Otto, who has one line of non-sung dialogue in the original show, and here gets his own romantic subplot.
- Bi the Way: Hänschen decides he's tired of desperate girls who use him for Dating What Daddy Hates—and decides to go after Ernst and his nice ass.
- Big "YES!": Melchior when Black asks if he killed Moritz.
- Brooding Boy, Gentle Girl: Melchior thinks serious thoughts about institutional racism. Wendla brings him tea in detention.
- Canon Foreigner: For the Harry Potter universe, almost the entire cast. The only canon Harry Potter characters (since the story is set a good century before Harry and friends arrive at Hogwarts) are Headmaster Phineas Nigellus Black and Professor Merrythought. They take the place of Spring Awakening's Herr Knochenbruch and Fraulein Knuppeldick.
- The Clan: The Rilows are a pureblood Gryffindor clan. Hänschen and his sisters are among the only half-bloods and definitely the only Slytherins.
- Darker and Edgier: Though it's a little tame by Spring Awakening standards, it deals with some more adult themes than Harry Potter, including sexual abuse, suicide, abortion, and the heyday of the anti-Muggle-born racism we see in the '90s Wizarding world.
- Deadpan Snarker:
- Hänschen Rilow.
Melchior: Shame we couldnt have had them for Ravenclaw,
Hänschen: Wasnt likely, since their brains have some practical use.
- Melchior gets a few good ones too.
Georg: O.W.L. results are in the headmasters office."
Melchior: And you think if you sit here long enough theyll shout them down the stairs to you?
- Disabled Love Interest: Since Something Wicked is based on the Deaf West revival of Spring Awakening, Wendla and Ernst are this for Melchior and Hänschen, though it isn't commented on.
- Otto and Anna are this for each other, since he's Deaf and she's in a wheelchair.
- Disproportionate Retribution: Admittedly, Melchior got into a screaming match with Professor Merrythought in the middle of her class, but he serves detention in a dungeon cell.
- Does Not Like Shoes: The first man Ilse meets in Priapia.
- Erotic Dream: Moritz has his first one after Melchior takes him to a burlesque show.
- Females Are More Innocent
- Forceful Kiss: Ernst has a bruise on his lower lip after Hänschen is done with him.
- Hormone-Addled Teenager: It is Spring Awakening, after all.
- Last-Name Basis: Hänschen and Bobby Maler tend to indulge in this.
- Lighter and Softer: Than Spring Awakening. The sex is not described explicitly, there are only two f-words rather than eleven, and of the three masturbation scenes in the original, one (Mirror-Blue Night) is cut completely, and the other two are only obliquely referenced.
- Love at First Sight: The very first line of the fic is "Otto Lämmermeier fell in love as soon as he got on the Hogwarts Express."
- Mr. Fanservice: Melchior is this in-universe, as most of the girls find him attractive.
- Muggle Born of Mages: Ernst's mother is this, so even though he's only one generation separated from the Wizarding world, he still falls under suspicion when the teachers are questioning Muggle-borns, more so when they find out his mother is related to Moritz.
- Named by the Adaptation: Martha's father, unnamed in Spring Awakening, acquires the first name Gustav.
- Precision F-Strike: Twice, both coming from Melchior.
- Profiling: Merrythought and Black do this to the Muggle-born students.
- Sadist Teacher: Black and Merrythought both count as this.
- Sex Equals Love: Wendla believes this about herself and Melchior.
She began to cry again. "You said love was the only magic strong enough to create life, and look at me. He loves me, he does, he does."
- The Talk: Mama explained that to have a child, a husband and wife cast a spell together, and because love is the most powerful magic in the world, it creates a life where nothing else can."
- Twin Telepathy: Thea and Melitta say they have this. Hänschen doesn't believe them.