I've always wondered what would've happened if Draco had taken Dumbledore up on his offer at the end of HBP, when he said that the Order would protect Draco and Narcissa. Here is my take on what would've happened if Draco did take Dumbledore's offer.
"...I can help you, Draco," Dumbledore said, strongly. He leaned against the stone tower behind him, beneath the greenish glow of the Dark Mark, set high in the sky.
"No, you can't, Draco responded. His wand hand shook badly as he pointed it toward Dumbledore. "Nobody can. He told me to do it or he'll kill me. I've got no choice."
"Come over to the right side, Draco, and we can hide you more completely than you can possibly imagine. What is more, I can send members of the Order to your mother tonight to hide her likewise. Your father is safe at the moment in Azkaban...When the time comes, we can protect him too...Come over to the right side, Draco...you are not a killer..."
Draco stared at Dumbledore, slowly taking in his words.
"But I got this far, didn't I?" he said, carefully thinking about the exact words that he would say. "They thought I'd die in the attempt, but I'm here...and you're in my power...I'm the one with the wand...You're at my mercy..."
"No, Draco," said Dumbledore quietly. "It is my mercy, and not yours, that matters now."
Draco did not know how to respond to this. His mouth dropped open and though his wand hand was still trembling, he slowly lowered his wand. He nodded and took a step toward Dumbledore.
"I...I don't know if I should trust you."
"Have I ever given you reason to not?"
Draco did not say a word. His hand still shook, though it lay at side. "You can protect my mother?"
"And we can protect you, Draco. Lord Voldemort will, no doubt, try to kill you. He is not happy with you nor your family. We can hide you. We can protect you."
Slowly, Draco nodded again. "I...I...protect my mother. I don't want her to die because of me."
"You will accept our help, Draco?"
Draco nodded again. He blinked away tears in his eyes. "Yes," he said in a voice barely above a whisper. "I want your help."
Dumledore smiled at him. He weakly waved his arm toward the area where Harry lay, immobilized and silenced. "Since...since I am without a wand at the moment, would you do me the honor of performing the 'Finite Incantatem' spell over there, please?"
Draco gave Dumbledore a confused look, but raised his wand. He nervously glanced over his shoulder at the stairs, hearing the sounds of warfare near.
"Go on, Draco," Dumbledore said, kindly nodding.
"Finite incantatem," Draco said, waving his wand in confusion.
At once, Harry regained use of his body. He stood up, still beneath the Invisibility Cloak, and held his wand toward Draco.
"Harry...Harry, please reveal yourself," said Dumbledore.
Harry pulled off his Invisibility Cloak and Draco's eyes nearly bugged out of his head.
"Potter!" he called.
"Draco, the pair of you are on the same side now. I must ask you to set aside whatever past differences you have with one another to work alongside each other now. Or, I must ask for a lack of open hostility."
Harry nodded, biting his lip. He remembered when Dumbledore uttered these words to Sirius and Snape and how they didn't really abide by them. That was probably one of the contributing reasons why Sirius felt the need to go to the Department of Mysteries a year ago.
"Draco?" asked Dumbledore.
Draco looked between Dumbledore and Harry, unsure that he had made the right decision.
"Draco?" prompted Dumbledore. "Will you agree to a lack of open hostility?"
He slowly nodded and jumped at the sound of banging behind the door.
"We must act quick. Harry, send your Patronus to Hagrid and tell him that we need a guard for Draco and Narcissa Malfoy at once."
Harry looked at Dumbledore in confusion. "Professor, how-"
"Just think of the message as you are performing the charm. Quick, now."
A magnificent stag lit up the tower and galloped down the Hogwarts grounds. The sounds of banging and yelling drew closer. They sounded as if they were right on the other side of the door. Draco looked worried and raised his wand arm, shakily.
"Harry-Draco-get under the cloak."
Harry and Draco gave each other a look of discomfort, but Harry nonetheless threw his Invisibility Cloak over the pair of them. A screech from somewhere below them. Draco looked at Harry uneasily. Suddenly, Buckbeak emerged from below the sides of the tower.
"Harry, Draco, get on," Dumbledore said urgently, as the sounds were now penetrating the door. "Hurry."
Harry ran over to Buckbeak, half-dragging Draco along.
"No way," Draco said. "There is absolutely no way I am getting on that thing."
"Hurry up, Malfoy!" Harry gave Draco a little shove and together, the two of them jumped on Buckbeak's back.
"Harry," Dumbledore said, facing Buckbeak and Harry and Draco. "Bring Draco to the Shrieking Shack and stay there for further instructions. It is imperative that Draco and his mother be kept safe. Request for Kingsley to escort them to headquarters."
Draco clutched Harry's shoulder tightly.
"But, Professor, what about you?" Harry gestured to Dumbledore's weak hand.
"I will be fine. Harry, one more thing." He wordlessly handed over a small, golden locket. "Take care of it, Harry."
Harry nodded. "Professor-"
"Go. Now!" Dumbledore urgently said. He clapped a hand to Buckbeak's side and they took off at once. Draco clutched Harry's shoulder tighter that it was starting to cut off circulation. They flew higher into the sky before diving down into the Hogwarts grounds. Harry did not know how he could steer Buckbeak toward the Whomping Willow, but somehow he managed to lead him in the correct direction.
"Get off, Malfoy!" Harry yelled. He shoved Draco off and threw the cloak from him. The two of them bent down to the ground, avoiding the tree's branches trashing around. He pulled out his wand and waved it toward a small branch on the ground.
"What are you doing?" asked Draco, panicked.
"Wingardium Leviosa!" The branch levitated slowly and easily prodded a small knot on the tree. At once, the tree froze and Harry shoved Draco to a small opening in its trunk. "Get in there - hide!" He turned toward the castle and pointed his wand. Again, a stag protruded from its tip and headed toward the front doors.
"Shut up, Malfoy!" He looked up at the tallest tower and saw shadows. There was a crowd of people gathered up there, he surmised. A part of him was itching to head back up.
"Harry! Harry, what-?" Kingsley's deep, booming voice echoed around him. "Where is Draco Malfoy?" he asked, his wand arm outstretched.
"In there," Harry said, pointing toward the frozen tree. "Malfoy's in there." He glanced up at the Astronomy Tower. "What's going on up there?" he asked sharply.
"Draco," Kingsley called into the tree. "Come out, Draco."
"He's wearing my cloak, Kingsley."
"Draco, reveal yourself."
"No." Draco's defiant voice came from Harry's right side.
"Draco, take my hand," Kingsley said staring at the blank space next to Harry. "We will leave at once."
His calming voice seemed to have that effect on Draco. Scared, Draco reached out his hand and grabbed Kingsley's arm. Kingsley reached around Draco and put his arm around him.
"Harry," he said. "We must borrow your cloak."
But Harry wasn't paying attention. He was already looking back up at the Astronomy Tower. "Yeah, yeah, okay," he said, waving them off.
"Let us go, Draco." Kingsley and an invisible Draco quickly headed toward the front gates. Harry knew that they would Apparate once they had reached the barrier that separated Hogwarts from the outside world.
Harry barely waved at them as he jumped atop Buckbeak and headed as fast he could toward the tallest tower of the castle.
Thanks for reading! Please review and let me know what you think!