Lucius Malfoy was the one to blow the Astronomy tower door open, once he did that all of the Death Eaters stormed into the tower. Hermione heard a shouted "Expelliarmus" from Draco and quietly snuck into the tower and hid in the shadows and watched the scene unfold before her.
Dumbledore was standing in the middle of the tower, calmly gazing at the group of Death Eaters before his eyes landed on Hermione. Hermione held her breath and hoped that the other Death Eaters wouldn't look at where the headmaster was staring. Dumbledore sent a small nod her way and turned back to the assembled group of Death Eaters.
"I must admit I wasn't expecting this tonight. Am I right to assume you are here to kill me?" asked Dumbledore as he calmly surveyed the group.
Draco stepped forward after his father pushed him and said with a sneer, "Yes, I must finish my task."
Dumbledore fixed Draco with a kind gaze, "Draco my boy, you are not a killer, there is too much good in you."
Draco scoffed, but in his eyes there was a look of gratefulness.
"I see that you don't believe me, but before you kill me, answer an old man one last question. How did you manage to get into the castle?"
"It was simple really, I used the vanishing cabinet in the Room of Requirement and you never noticed what was happening right under your nose!"
"I do believe you are correct Draco, I had no idea. Now since you have granted my wish you may get on with it. I am a man of my word," said Dumbledore with a peaceful look on his face.
Draco hesitated as he looked at the headmaster. Draco's wand hand was shaking as he brought the wand up and pointed it at Dumbledore.
"Do it," hissed Bella into Draco's ear, her face angry with a cruel smirk plastered on her face, but her eyes gave her away as there was a look of distinct sadness and pain.
"He can't do it! He's too weak!" gleefully shouted Greyback as he began to laugh.
Bellatrix whirled around and pointed her crooked wand at the werewolf. Greyback's eyes widened in fear and he snapped his mouth shut and backed away from the witch.
Bella turned around to face Dumbledore again, "Draco, do it!"
Draco swallowed one last time before opening his mouth to begin saying the curse.
"Avad-"
Suddenly, he was shoved out of the way and Snape stood tall pointing his wand at the headmaster.
"Severus…," pleaded Dumbledore as he looked at his college.
The potions master looked at the headmaster and with a very small nod, one that could easily have been missed if one wasn't paying as much attention as Hermione, he held out his wand pointed at Dumbledore with a stoney expression on his face.
He hesitated again until Dumbledore spoke once again, "Severus, please.."
"Avada Kedavra."
The Headmaster fell off the tower when he was hit with the spell and he plummeted to the ground. Hermione could only watch with silent horror as the wizard fell, she couldn't make any noise as she didn't want to be caught by the Death Eaters. One of the Death Eaters cast Voldemort's mark in the sky. Hermione froze in her hiding spot as all the Death Eaters except Bella and Draco stormed past her laughing as they set to work destroying the castle. Bella and Draco stayed in the tower under the guise of Bella lecturing Draco. Lucius couldn't be bothered to stay in the tower with them as he wanted to terrorize some students and destroy some paintings.
"Draco how dare you bring shame on our family like this! Do you have any idea how angry the Dark Lord will be?!"
"I'm sorry Aunt Bella. I-"
The Death Eaters were finally far enough away from the Astronomy tower and Bella immediately stopped her 'lecture' and rushed over to her nephew and quickly engulfed him in a hug. Draco burst into tears the moment his aunt wrapped her arms around him.
"Why did he have to die? Why did it have to be this way?" asked Draco not wanting an answer as he already knew why.
"I don't know, Drake, I don't know. But we need to stand tall and play our parts and then when this is all over we can mourn," comforted Bella with a sigh as she released Draco.
Hermione took this as her moment to announce her presence. Hermione stepped out of the shadows and cleared her throat quietly.
"Granger! What are you doing here?!" asked Draco as he pointed his wand at her attempting to hide the fact that he was crying.
"For similar reasons as you I suppose. I knew something was happening so I followed you here."
"Draco, put your wand away! Clearly Hermione isn't a threat to us," huffed Bella.
Draco stared at his aunt confused as to why Bellatix was referring to Hermione with familiarity, but put his wand away nonetheless. Bella put a comforting hand on Hermione's shoulder and Draco opened his mouth to ask what exactly was going on. But then a loud and angry voice interrupted the trio. Bellatrix immediately drew her wand and pointed it at the voice.
"HERMIONE! What are you doing with them?!" shouted Harry as he threw the invisibility cloak off of him.
Hermione's eyes widened comically as she realized that Harry had been there the whole time, "Harry this isn't what you think it is, but we don't have the time to talk about it right now. We have to stop the Death Eaters rampaging in the castle."
"What do you mean we?! Malfoy he trusted you! He let you into the Order and you betrayed him! And do you know who she is?! She tried to kill Sirius and tortured Nevile's parents," exploded Harry with rage.
Bella winced at the reminder of the horrible things she did in the past as she put her wand back in it's holster, "I won't deny that I did unforgivable things in the past, but that's not who I am anymore and I don't ever want to hurt anyone like the Longbottoms again. And I didn't try to kill Sirius, I just needed him to stop trying to kill me."
"Harry we don't have the time for this! I'll explain everything when this is over, but we need to get the Death Eaters out of the castle. Please Harry trust me," urged Hermione.
Harry looked like he was going to argue until he heard the terrified yells and shouts of some students.
"Okay, but you need to explain everything to me," said Harry as he drew his wand and made his way to the door. "Are you coming?"
Bella, Hermione, and Draco immediately began to follow him to the door. The group had quickly agreed that Bella and Draco would go first and find the Death Eaters as Hermione and Harry followed behind under the invisibility cloak.
Everything was going to plan until they heard the panicked shouts of the Death Eaters as they ran past them to the Room of Requirement.
"What in Salzar's name is going on?!" shouted Bellatrix.
"The aurors are coming!" screamed one of them.
At that Bella grabbed Draco by the arm and hissed at the two under the cloak to find a professor or an auror. Bella grabbed Draco by the arm and the two ran to the Room of Requirement. After the abrupt departure Harry pulled Hermione into a secluded corner nearby and tugged the invisibility cloak off of them.
"You'd better explain everything when this is all sorted out," said Harry.
"I know and I will, but first we need to get out of here."