Twilight Sparkle was in the throne room sitting near the map. She wanted to be there anyway even if the map didn't call her. She looked around at the room to see that everything was properly cleaned up and evening was in order.
After she sat there for a bit she decided to go to her room and rest for the evening since she didn't have anything scheduled. As she went to her room she could hear noises coming from her room. She grew annoyed as she hoped nopony was in her room.
She decided to sit up and go up to her room to see who was in there. She walked up to her room and listened for a bit and she heard some pages turning. She became furious. Nopony was supposed to go in her room and touch her stuff. She opened the door and saw that Starlight was looking through her books. Twilight remembered this happening before and she warned her to never do it again.
"Starlight!? What the hell are you doing!? I told you to never go in my room but look at you! Your in my room! Didn't you listen to me!? Don't you even remember what the consequences where? Twilight yelled.
"Twilight...I'm sorry...I just wanted to..." Starlight began to say but Twilight didn't want to hear what she had to say as she interrupted her excuse by levitating her out of her room by her magic and bringing her out to the main hallway.
"I told you last time that my room was off limits last time but you decided to go there anyway. I feel like I can't trust you anymore. Your not getting another chance!" Twilight said as she grabbed a horn remover. Starlight started to get really scared.
"No please don't remove my horn! I want to continue to practice spells!" Starlight begged her but it was to late as Twilight held Starlight down and put a magic dampener on her horn and then she cut Starlight's horn straight out of her head Starlight began to sob heavily she could never do magic ever again.
"That's your consequence! I warned you and you didn't listen! Get out of my castle and don't come back! Do you understand!?" Twilight yelled. Starlight sobbed heavily as tears leaked from her eyes.
"I said do you understand!?" Twilight screamed at her ex student. Starlight Glimmer nodded and got up and left while she cried with despair. Starlight ran far away as Twilight watched her. Twilight slammed her door shut and mumbled angrily. She saw Spike and spoke to him.
"I warned her! I told her to never go in my room and touch my stuff and she does it anyway. She was a bad listener I can't believe I had her as a student." Twilight ranted. Spike shrugged at Twilight and he responded.
"Well what are you going to do for a student now?" Spike asked as he was curious as to what Twilight would do to teach another student. Twilight rolled her eyes as she knew that she didn't want to get another one at that moment since she just lost one.
"I don't know yet I'll try to teach another one next year. I just hope nopony challenges me over my decision to force Starlight out. My friends might but then again they might not as they weren't to close to her." Twilight said. Spike nodded.
Twilight and Spike sold Starlight Glimmer's stuff as she wasn't going to come back for it and then once they were finished with that Twilight told her friends about what happened.
Twilight wrote a letter for Princess Celestia about what happened while also writing about how she wasn't ready to get a new student. She sent the letter to the princess and cleaned out Starlight Glimmer's room.
Meanwhile Starlight Glimmer had ran far away from the castle as she had been expelled by Twilight. She had no idea where to go next since she had ruined her own life by betraying Twilight's trust as she walked away from Ponyville.
Meanwhile Celestia ordered for all of Starlight's belongings be transferred to her as she didn't have any stuff the first time she became Twilight's student as Twilight had given her materials and other stuff to use but since she was gone now she decided to take that stuff back.
After she got the stuff back that she had given to Starlight Twilight and Celestia had a discussion on a new student Twilight could teach since Starlight had betrayed her trust but Twilight declined the offer as she didn't want another student after what happened so Celestia didn't give her another one.
Celestia congratulated Twilight on all the hard work she had done in trying to teach Starlight even if it didn't turn out to well in the end. Twilight thanked her for the congratulations that she had given her.
After that Twilight and her friends removed Starlight's chair from the cutie map table and donate to get a bit more currency. Twilight knew that Starlight was going to touch her room again but she regretted that she didn't do anything to prevent Starlight from going into her room.
It took a while for Twilight to get over about what Starlight did and when she did she felt better since she didn't think about it anymore. She hoped she wouldn't see Starlight again as it would be embarrassing if she ran into her former student.
She also hoped that Starlight wouldn't turn back into a villain again as that would force her to see her again if she had to save Equestria from Starlight and reform her again but she calmed down as she remembered that Starlight wasn't a threat since she had her horn removed so she relaxed.
Twilight moved on from the incident as she continued to save Equestria with her friends whenever Equestria needed to be saved while continuing to do diplomatic journeys as well but she would always think about her student from time to time as Starlight would never leave her memory.
