The RP will take place the very first year Hogwarts was open after the battle in book seven. Even with magic, it took one year to repair it, and during that year parents of school aged children had to educate their children themselves, which has led to a lot of students(first years in particular) having a widely varying level of skill and correct knowledge.  Thirteen year old Jackson (Jax) Dobs returns to Hogwarts after a year living with his muggle parent(can't decide which parent was magical). During that year, to keep up with studies so he could stay in the appropriate school year, he was forced to study independently. The only knowledge base he had for DADA was actually the literal Dark Arts education that the Carrows taught. So upon return to school he feels as if the DADA education is severely "watered down." To make up for it, he starts a secret society at school, akin to Dumbledore's Army, but with the goal of giving students a more complete knowledge and understanding of the Dark Arts. He believes that magic is only "Dark" when it's used for evil, and so even the most cruel or macabre spells could be "good" if they were used against "bad" guys.  
His society has the same visceral, unforgiving teaching style that the Carrows were infamous for. Students are pitted against each other in all out magical slugfests. Sure, sometimes disarming is the right trick. But what if they have a second wand or some other protection? Better Crucio that unarmed wizard just to be sure. 
This club is not only against school rules, but against wizarding laws, and so keeping it a secret has the highest of stakes for those in it. Jax will use the most unsavory tactics to keep people quiet.   
And let's not forget what's happening outside of the Room of Requirement. Minerva McGonagall is the headmistress now, and other than her ascension to that office and replacement as both Transfiguration teacher and head of Gryffindor, the staff remains mostly unchanged. The only three new teachers are for DADA(of course) Muggle Studies(the previous one, I believe was killed and replaced by Death Eaters) and Transfiguration.

Teachers:
DADA: 
Potions: Slughorn (Head o' Slytherin)
Charms: Flitwick (Head o' Ravenclaw)
Transfiguration: 
Herbology: Sprout (Head o' Hufflepuff)

Name: 

Date of Birth: (Current date is September 1st 1999).
  
Appearance: Pictures okay, but no anime style, please. If you like, you can list stats instead of describing in prose(hair color, eye color, height weight, etc).  

Blood Status: 

Personality: Short but to the point, give me a good basic gist.  

Wand: Leave blank, wand chooses wizard y'all.  

House: Leave blank, don't put the Sorting Hat out of work. 

Best Classes: You'll be First years, but I'm sure you have in mind what your character is good at. 

Worst Classes: These two are both extremes, so whatever isn't in either list you can be considered roughly average in.  

History: