It was a rather anticlimactic end to the most feared Professor at Hogwarts other than Dumbledore. Baiting him into a confrontation on Harry's home ground and then destroying his willpower with the hard facts of his oxygen thieving existence made it a breeze to capture his mental avatar.
Harry turned it into a holodisk and duplicating all its memories took only seconds. Coming out of his mindscape to see Snape still reeling from the failure of his mind probe allowed him to easily hit him with a stunner and strip him of anything that may help him escape. Seeing his wrinkly balls was a small price to pay to make sure he was not hiding a portkey that could alert Dumbledore to Harry's true nature.
A dive into the jumbled mess that made up Snape's worthless existence had Harry facing a multitude of memories that were either fake or not relevant like reading the newspaper over breakfast. Since he already had a complete copy of Snape's entire mind, this type of defence became useless, even if it was an automatic response because Snape was unconscious.
Harry started destroying everything in sight. From treasured childhood memories of Lily to potion recipes, he cared not what they were as long as he made it to Snape's centre. Surprisingly, the continual destruction of Snape's mind must have jolted him awake because the memory bombardment was quickly halted, and the ghostly image of Severus 'the petty tyrant' Snape appeared.
"What is the meaning of this Potter? How dare you invade my mind! How are you even able to?" Snape demanded, so confused by the event he blurted out two questions while expressing his outrage.
'Weird, does my avatar now look like Harry Potter? Could it be because I swore a magical oath that my name was Harrison Chad Peverell and that all contracts must use my full name? Did it somehow change my perception of myself to now look like my current body?' Harry thought to himself, so many questions at Snape's reaction had him zone out for a couple of seconds. But he quickly regained his focus, to act carefree in another's mind was a foolish thing to do.
"Of course you would not know how I am here, after all, I captured your avatar after your failed attempt to mind rape me! Your last thought would be casting the Legilimens spell." Harry replied to Snape's mostly rhetorical questions.
"Impossible! You are only a child that just found out he is a wizard!"
"Yeah, about that. I already explained that to your avatar and can't be bothered going through it again. Surrender, or I will turn you into a drooling dunderhead, incapable of wiping your own arse." Said Harry offhandedly.
He had no intention of doing so, but after his earlier rampage through Snape's mind, it was a genuine possibility if he continued. Not that Snape knew he already copied all his memories and could add them back. Or that Harry could just modify the captured avatar and release it back into Snape's erased mind.
Knowing that Snape would never voluntarily surrender, he used the momentary bewilderment his reply caused to throw out some attacks. Although Harry had copied all of Voldemorts techniques and skills, he had very little actual fighting experience. This would be a perfect time to get some practice as Snape was actually a competent dualist. What followed was a frenzied dogfight that would have seen Harry lose if it was not in a mindscape because the attacks only weakened his mental projection/representation.
Since he would be under the scrutiny of the wizarding world, Harry decided to fight like a wand wizard and only use well known 'Light' or 'Neutral' spells that even Dumbledore would not be able to complain about. Even weakened as he was, Snape managed to actually come close to 'winning' until Harry stopped fooling around and unleashed his full powers on the unsuspecting bully. It had been a valuable training experience, but he was not stupid enough to put himself in danger for it like some idiot Chinese cultivator protagonist.
The different dodging and duelling stances, coupled with alternating chains of various spells and counterspells from Voldemort's memories, made a rookie like him nearly Snape's equal. Even if he was already mentally weakened from his failed mind probe that saw part of his soul captured.
But Snape's vastly superior experience at wizard duelling thanks to his Death Eater days, saw him slowly gaining the upper hand. Since that was the case, Harry just f*cked him up by summoning Enclave power-armour soldiers to attack him while he blasted Snape with waves of area effect spells aimed at his feet so he couldn't dodge them.
Harry didn't even give a Bond villain speech after slaughtering Snape, he just erased everything in his mind when he captured his 'mental hub'. He then retreated back to his own mindscape to alter the captured avatar's memories. His earlier idea had been a stroke of genius as Snape at the moment was like a newborn child straight out of the Uterus. Anything he added or deleted would be branded on the clean slate that was now Snape's soul.
'Wait a second. Did that mean that is also wiped out any magical oaths?' Harry suddenly thought.
He quickly scanned the newly captured thoughts for the oaths or contracts that the idiot made to Voldemort and Dumbledore. It turned out that there was only the slave seal or 'Dark Mark' from Voldemort, but Dumbledore made him swear a magical oath when he went grovelling to him to save the Potters.
It was a basic loyalty pledge concealed within the denouncing of his Death Eater ways and obsession driven promise to protect Lily. It was nothing that Snape would have immediately protested against, but after Lily died, it was changed automatically to protecting Harry under Dumbledore's guidance. This did not mean he had to be helpful or anything to Harry Potter, only keep him alive.
His malicious bullying campaign against the ignorant, shy orphan boy was proof of that. There was literally no reason for it other than Snape's hatred of James Potter, and the bitterness of Lily's death coupled with having to keep the Potter spawn alive. His views on that could easily be seen by how he begged Voldemort to spare Lily but not her child! Not even 'Slytherin camouflage' was a good enough reason for his over a decade campaign of traumatising children.
Really, Voldemort fell straight for the self-fulfilling prophecy trap that ninety-nine percent of all completed prophecies reveal. Snape should have advocated for the capture of Lily and her child while killing off Potter. After a quick brainwashing, Severus Snape would have been the new Potter regent after marrying Lily and could 'raise' Harry to be Voldemort's most avid follower. He could have got everything he ever wanted.
But no, the idiot had to f*ck everything up and railroad himself into the most miserable existence he called his life, a child-hating potions teacher in the place where all of his most hated memories and traumas took place. Harry found it hilarious that Snape caused all his own detrimental predicaments and thought the best way to fix them was by terrorising a child while doing his best to keep the child alive so he could continue to torment him.
Regardless of Snape's stupidity, Harry saw no physical or magical evidence of an oath other than a faded Dark Mark branded on his soul. But that was a different can of worms that was important since Harry could use it for his own purposes thanks to Voldemort's knowledge.
There was no sign of the magical promise to Dumbledore, so he could only leave it for now and test it out later on wizards that would not be missed if they died. Since the oath revolved around him anyway, he could just cut Dumbledore out of the picture and have Snape become a triple agent!
After he was done modifying the avatar, Snape was now dedicated to doing everything he could for the child of his beloved. Though Harry had to call his house-elves to reclothe him before waking him up. Stripping him in the first place was already a memory he wanted to erase, let alone adding that experience to it.
Severus would now happily jump in front of a killing curse to save Lily's child, the only remaining part of her and the reason for his continual existence. He had met with Harry to talk about their misunderstanding in class. The subsequent discussion unearthed Dumbledore's manipulations and solidified his need to protect Harry and become a spy for him against Dumbledore and Voldemort.
A few words of how 'Slytherin' it was of Potter to try and blackmail him, but then apologised when it didn't work, would hopefully be enough for the little snakes to give him some grudging respect and leave him be. Of course, if they tried to get 'even' for any imagined slight, he would put them down, hard.
It was a shame that Harry couldn't confirm the process of erasing magical oaths by wiping a soul of all its thoughts and then inserting modified memories back onto it as a viable method. But for now, he was happy that he had Snape working for him and that it would keep the Slytherins off his back.
Only ten minutes had passed since he first teleported to the potion class, but he had spent a couple hours in mindscapes playing with memories or trashing Snape for fun. The time difference was just one more reason why Occlumency was overpowered and why wizards had grown weak.
House-elf travel back to where he disappeared after dinner, saw him making his way back to his room. He didn't want to give the magical portraits to many clues about his activities through his movements. He would not be seen walking back and forth trying to find the Room of Requirements when he could just appear inside it thanks to his faithful minions teleporting him. Although, leaving so he could change the room would require him becoming invisible or moving portraits.