In this alternate universe, Twilight didn’t read the legend of how Celestia defeated Nightmare Moon; thus, she never sends a letter to Celestia to inform her about the prophecy. Twilight didn’t receive a response from Celestia, so she never went to Pineville and did not meet the other ponies.
 
When Nightmare Moon appeared before the Summer Sun Celebration and brought havoc, Celestia went to stop her, Twilight was worried for her mentor, fearing that the worst might happen she went to the Canterlot Archives, there hidden, was the Alicorn Amulet( Twilight discovered it ones and was lured by its power, Spike told her that someone was coming so she quickly hid it back and left the archives). Twilight took it and put it on and with great speed galloped to the Castle of the Two Sisters, while running towards the castle, she felt that something was wrong with the amulet but she was in to great of a hurry to consider the problem, upon her arrival she was terrified to discover that Celestia was losing the battle, Nightmare Moon was about to kill her but Twilight jumped in front of her mentor to defend.
 
Twilight started fighting fiercely and found that the amulet was giving her enough power to be a match for Nightmare Moon, however after a while Twilight was tiring out and couldn’t keep up with Nightmare Moon any longer, luckily for her Celestia was able to recover partially and together they managed to barely defeat her.
 
After a couple of moments catching their breath, Celestia started commending Twilight for her help and bravery, but Twilight wouldn’t listen, Celestia was wondering why she didn’t respond to her words, she made a couple of steps towards Twilight to see what was going on, but stopped when she noticed Twilight was emitting somewhat of a malevolent aura, Celesta quickly noticed that Twilight was wearing the Alicorn Amulet( she didn’t notice it during the battle). Celesta demanded Twilight to take it off but again with no response, instead what followed send shivers down Celestia’s back, Twilight looked at Celestia with such bloodcurdling eyes that her heart stopped, the whole place filled with dread, even Nightmare Moon who was greatly weakened lying on the ground, found herself breathing heavily from the pressure in the air.
 
Before Celestia could utter a word Twilight teleported in front of Nightmare Moon, the mare of the night tried to attack her with a blast from her horn but Twilight canceled it out with her magic and immediately after broke her horn. Celestia was shocked, she couldn’t believe what her student had done, she quickly shouted at Twilight to stop, in response Twilight nodded her head and uttered a couple of words towards Celestia that left her horrified, Twilight then ignited her horn and engulfed the barely breathing mare in magic, Nightmare Moon could feel her body transforming into magic itself and being drained into Twilight’s horn, she couldn’t do anything, her tired out body didn’t have the strength to fight back, the only ting she could do was look at Celestia for the last time, her body had vanished all that was left was her armor, Celestia ordered Twilight to explain the meaning of her actions, Twilight teleported again in front of Celestia, at that moment Celestia knew what was wrong, it was the amulet that had corrupted the young mare.
 
Twilight was emitting a high amount of energy, Celestia could feel Nightmare Moon’s magic emitting from her as well, Celestia tried to reason with Twilight but it was pointless, Twilight wasn’t just going to give way all of this unbelievable power just because Celestia was begging her, she instead ignited her horn ones more and engulfed Celestia’s body in magic, Celestia tried to use her magic against that of Twilight’s, but Twilight canceled her magic the same way she did with Nightmare Moon, as Celestia’s body begain to turn into magic, her eyes started filling with tears, she could not belive what her beloved studdent had turned into, Celestia didnt say a word, she only gave Twilight a glance of sorrow. Celestia’s body was fully turned into magic which Twilight absorbed, Twilight’s power grew exponentially, her aura alone scared away most of the creators living around the castle and all of the plants close to the castle started to die out. Twilight was irreparable, the amount of power and the amulet had corrupted her to no end, Equestria’s future was looking horrid and unsure.
 

 
I had this idea for an evil version of Twilight but just did a drawing of her, after around two weeks I looked at the drawing again and this time I got more into the idea, so I made a backstory for her. So what do you guys think?  
since this is a second alternate universe to the original story of the show, I think I’m going to call it “Bad Drive”. It probably sounds silly but I can’t think of another name.