After Harry could see that his two supposed captors had fallen asleep, he brought his arms out with all his might. After climbing up fifty feet of rope with nothing but his arms, breaking these cords wasn't a problem. The silencio charm Snape had put on him ensured that they wouldn't hear him as he broke the ropes. Harry looked around and found his wand then apparated back to the tavern to find the bar keep knocked out cold and Sean enjoying a mug of some kind of drink, most likely milk, with his duffle in hand.
"What happened here?" Harry asked his mentor and friend.
"It was closing time and he tried to throw me out," Sean said as he approached Harry and took his arm. "Is everything ready?" Sean asked Harry.
"Yes," Harry replied, "both of them are asleep and they have already sent off the message."
"Let's go then," Sean said with a serious tone of determination…and they were off.
The loud pop of them apparating woke up Snape and Bella who looked into the night to see two figures standing in front of them. One they recognized as Harry with his wand drawn ready to fight, they could see the other one was about two inches shorter and holding two swords with the blades resting flat on his shoulders and crossing behind him. The light of the twilight sky reflected off of Sean's blades and showed his emotionless face.
"Ever vigilant," the shorter figure said to the two Death Eaters before them, "one rule the Dark Lord obviously didn't teach you."
Fear came to Snape's face as he realized that he was trapped, he could not probe either of their minds, and he knew the Dark Lord would never forgive he and Bella if they lost Potter now.
"Gosh Snape," Potter said in a cool monotone voice, "quit thinking so much or you'll give me a headache."
Harry paused to let his statement register before adding, "You're right about Voldemort not forgiving you for losing me at this point, especially since my companion is a Muggle."
"Let me kill the Muggle Severus" Bella said in her evil and malicious voice, "and you put the boy back to bed."
Snape could only nod. Bella waved Sean over to a space about half a mile to the side of Snape and Harry. They went there to duel while Harry never averted his gaze from Snape.
"It would seem that someone has taught you illegumency," Snape said to Harry trying to remain cool and confident.
"A lot more than that," Harry stated coolly to Snape, "read my mind now and see if you like what you hear."
Harry let his mental guard down long enough for Snape to hear him think "I'm going to kill you now for what you did to Dumbledore, bastard."
Snape was scared out of his wits at this point, he knew that Harry wasn't bluffing, that he was more than able, and that he wasn't about to hold back. Harry and Snape performed the usual ritual before a wizard's duel, then prepared to battle.
As Snape and Harry prepared to duel, Sean and Bellatrix had stopped and prepared to duel.
"Now listen you Muggle pig," she spoke with pride and disgust as Sean sheathed his swords, "I don't know how you primitive brutes fight, but we don't start until we cross our right arm and bow."
Sean went through the motion as Bella did the same. "Avara Kedavra!"
These would be the last words Bellatrix LeStrange ever said clearly. As she yelled the incantation, Sean spun to his right to avoid the green blast, taking out the knife on his right side as he did so, and then sprinted forward.
Before Lestrange could even utter the curse again, Sean had grabbed her wand with his left hand, brought the large knife in his right up and through the wand, then moved his body behind her and brought his right hand across her throat…performing a flawless wand slit.
"Im-pos-sible" Bella muttered as she instinctively clutched her throat and dropped to her knees.
As she dropped, Sean had sheathed his knife and unsheathed his swords; and in one fluid motion had brought the swords crossed into an x-shape to the sides of Bella's neck before she could even clutch her throat.
"Not bad for a primitive brute Muggle pig, eh?" Sean said confidently, he then brought his arms out to his sides, decapitating Bella. In a few seconds, a Muggle had defeated one of the most dangerous of Voldemort's Death Eaters.
At the scene of the other duel, Harry had performed the spin Sean taught him to elude spells, and then to Snape's horror and utter disbelief, performed stupefy without uttering or thinking it. Snape flew back a few feet, landing on his back and wondering what had just happened, and then saw Harry running towards him.
Snape raised himself up on his arms and tried desperately to read anything from Harry's mind but found that it was useless, all he could hear or see was water. Harry ran so fast that Snape couldn't utter anything as Harry brought his foot up under Snape's chin and kicked him with so much force that he flipped onto his back.
Harry then stomped onto Snape's chest with his right foot and kicked Snape hard in the ribs with his left. Snape let out a yelp of pain as he spit up blood.
Harry backed away from Snape, "Get up!" Harry ordered Snape in an uncharacteristically brutish voice.
Snape raised himself to his hands and knees. Harry brought his right knee right to Snape's face, breaking Snape's nose and sending him upright. Then without hesitation he brought his right leg onto the ground and kicked Snape squarely in the chest with a left turnaround sidekick, sending Snape onto his back.
"You're pathetic," Harry said disgustedly to Snape, "where's the intimidating potions master, where's the traitorous Death Eater who ratted out my parents, where's the one who murdered Dumbledore? Answer me!"
Harry looked at the sight of the professor who had intimidated so many of his peers, murdered his first mentor and father figure, and leaked the information that led to his parent's murder. Now all he saw was a beaten wretch of a man spitting up blood and struggling to even get to his feet.
Harry raised his wand, "now," he said to Snape with the monotone that he had gained from living and training with Sean, "you pay for your crimes."
Snape's eyes widened as he read Harry's mind and heard two of the last words he would hear on this world, "bleed pig!"
Then Harry said it, "sectumsempra."
The last thing Snape thought was simply "impossible, he's too young and it couldn't have been two and a half months ago I toyed with him…" then the spell took effect.
Snape had bled to death in about fifteen seconds, and Harry had watched him with the same emotionless expression he had on when Sean branded him. In a moment Sean came by with the head and cloak of Bellatrix LeStrange in tow.
"You won" he said to Harry simply and without any emotion.
"As did you." Harry answered with a similar tone. "What do we do now?" Harry asked.
Sean threw Bella's cloak over the arm that carried her head, then with his free hand unsheathed one of his swords and gave it to Harry.
"Patch up his face and take his head and cloak…leave the bodies for the buzzards."
Harry obeyed. He used a few mendo charms to bring Snape's face back to normal, only without any life in it. He removed Snape's cloak before decapitating the corpse with Sean's sword.
"We need to get back to the monastery now" Sean said, "we have a few days to prepare for the battle, and we need a bag and salt for the heads."
Harry nodded, understanding that the salt would act as a preservative. He would have been in awe that he had defeated Snape, but he had learned not to think anything of victory until the whole conflict was done. Harry gave Sean back his sword which Sean immediately sheathed, then put his wand in his pocket and held Snape's head in his hand by the hair. Sean made sure that Snape's wand was destroyed, after this he grabbed his duffle and Harry's arm. In another instant, they were back in front of the monastery.