Aside from the adventures into Ancient Magic by both Professor Fig and Alex, everything during the year had gone how one familiar with the Wizarding World franchise could expect. Poppy Sweeting had discovered the Golden Snidgets alongside Alex and a centaur's help, a fellow classmate's father had been saved by Alex from Ranrok's Loyalists and uncovered the reason why Ranrok hated wizardkind, and Alex solved both Rookwood's and Fitzgerald's trials--leading him to wait for the final trial to begin.

Erebus--when he hadn't been pestered by Alex--had also met Poppy Sweeting during Beasts class (or Care of Magic Creatures) and learned the Bombarda spell without incident. He had also learned the Transfiguration Charm from Professor Weasley's class, Depulso from Professor Sharpe, and Flipendo from Professor Garlick. He had considered learning the explosive fire spell Confringo, but decided to wait a bit on learning that spell since it seemed like he nearly learned all of the spells that a wizard could learn up to their fifth year at Hogwarts.

Through his connection to the Force, he could feel that his brief excursion to Hogwarts was nearing its end. Erebus knew that, at some point, the three of them would have to go to the final repository and defeat Ranrok to end the Rebellion for good.

He didn't mind that since this was only meant to give him a decent chance against some of the foes he would go up against in the future--including the Sith Emperor Vitiate when everything would come to a head during the Eternal Throne arc. The use of the Killing Curse at that point would be justified, but Erebus knew that he needed to have a higher proficiency in casting that spell before going up against the Sith Emperor.

It might also prove helpful against Thanos during the events of Avengers: Endgame.

'I know it will be a long time before I can return,' Erebus thought to himself as he received the notification from his System that Alex had found out about Ranrok's plans for the repository beneath Hogwarts. 'But when I come back, I'll be far more than prepared for Voldemort and the trials Harry will undergo. If Dumbledore doesn't get it in his head to not use spells on me that will piss me off, I might end up doing what Snape did to the old fool during Harry's sixth year earlier than planned.'

That's right. He was preparing everything in advance since he knew that the Ministry will bungle up everything even further during Harry's time.

Erebus had placed a strong and undetectable charm on the diadem that allowed him to easily find it--bypassing any sort of cloaking spell Tom could place on it--while also setting up other means to lay down traps for Tom Riddle's little game.

On the right-hand side of the third floor where--in the future--Harry and his friends will encounter Fluffy, Erebus harnessed the power of Shadow Magic to create another trap for Quirrellmort (Tom Riddle in Quirrell's body) by subtly displacing his five senses to make it a tad more difficult for Tom to locate the room. He didn't want Voldemort to have an easy time during Harry's first year at Hogwarts, but Erebus wasn't going to derail the whole plot since he too needed Harry to realize his destiny.

In the future, Erebus would have to make sure he got the Stone instead of Harry and letting Dumbledore destroy it--sort of like what the MC of Savage: The Night Wizard did with his Beast Powers. Nicholas Flamel didn't deserve to lose his source of immortality because of Voldemort's actions--even if the Stone would prove to be fake like in some fanfictions.

As for the Chamber of Secrets, Erebus had his own plans. He had gone into the girls' lavatory during the night--under the sight of the prefects and professors using his Cloak of Shadows skill--and opened the chamber's entrance. With that, he too set a Shadow trap for Tom to later activate during Harry's second year. This particular trap was simply nothing more than making sure both the fool Lockhart lost his memories just like in the books and movies while also guaranteeing Ginny Weasley's life.

Even though he self-taught himself his own Shadow Magic by using Arithmancy, Erebus knew enough of creating runic script to set the spells effects millennia in advance if desired. All these traps were essentially just conditional IF/THEN checks that ran whenever there was a disturbance in the environment, but also carried a set duration for activation.

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He was not going to let innocent people die if it could be helped. This would also be useful for people like Ginny Weasley who were simply caught in the crossfire between Voldemort's actions and Harry's trials that Dumbledore set up over the course of his seven years at Hogwarts.

Erebus didn't bother setting up anything for Harry's third year at Hogwarts nor for the next two years after that since he knew he'd be here to help deal with Barty Junior and the ever-hated Umbitch herself--although he wanted to personally ensure that bitch's torture himself with both the Cruciatus Curse and whatever he learned from Korriban. It was when he resealed the Chamber of Secrets and left to the Astronomy Tower that Erebus put one of the final parts of his plan into place.

Making sure that no one saw him there, he started to weave together a neat little trap for the future Death Eaters who would show up here when Snape would kill Dumbledore due to what Tom did for one of his Horcruxes. Erebus wanted to make sure that the Death Eaters suffered for their transgressions and, in this function, he made sure that the effects of the torture were equivalent to a fifth-degree Cruciatus like how the MC of HP: The Arcane Thief suffered due to a malevolent sadistic wizard for his petty theft.

Naturally, he excluded Dumbledore, Snape, Harry, and Draco from its effects. This trap was set to happen during the fatal spring evening when Snape kills Dumbledore, so no one could accidently trigger it before its time.

With the traps set, Erebus breathed out a sigh of relief.

'The future will be fine to deal with now,' Erebus thought to himself as he walked over and stared out into the starry night sky. 'I can't trust the fact that I might have caused some sort of disturbance due to the Butterfly Effect, but I also don't want Harry to be left completely defenseless since Dumbledore obviously can't be trusted with the task of guarding Harry. The old man left him with an abusive aunt and uncle as a mere baby, for gods' sake! Thankfully, I plan on making sure both James and Lily know what will happen to their baby hours before Voldemort would kill them. It is the least I can do for Harry aside from these traps.'

He continued to observe the starry night sky before making his way to the Map Chamber and the conclusion to his quest.

==+==

On October 31st, 1981... In Godric's Hollow...

Two boys--them being Albus Potter and Scorpius Malfoy--had finished their little plan of leaving a message for the future by writing it out on Harry's baby blanket. They were slightly relieved, but what neither them nor the adult Golden Trio could've expected was that in the moment they would capture Voldemort's daughter Delphi Riddle, an unexpected ally would appear.

"You have a lot of nerve, Delphi Riddle, showing up in this time period," the future Erebus Axus would hiss towards the clueless Delphi, "yet I knew that once you and the boys bungled up the first couple of chances to alter history, you'd come here to where it all began."

This sent Delphi, Albus, Scorpius, and the disguised Harry into a state of utter confusion since the first of them never knew about Erebus' existence while the others were dumbstruck at how he could appear here.

"You witches and wizards are not the only ones capable of travelling through time," Erebus muttered angrily as his eyes turned from beautiful blue to scalding orange-red like a proper Sith--even his wand glowing red.

"I will never allow the Augurey the chance to make Voldemort return! CRUCIO!" Erebus roared out as red lightning struck Delphi--faster than anyone could react to--and let her scream in pain. "I knew your plans and while I will not kill you, I will also not allow you to live in peace with the dementors in Azkaban for your crimes."

He then protected himself with a simple Protego when he sensed through the force that Hermione and the gang were attempting to subdue him. This prevented their attacks from reaching him even though he used an Unforgivable in front of them all.

"Let this be a reminder to you, Riddle, that messing with time is a dangerous thing," Erebus sternly told the girl who was no doubt feeling immense fear from Erebus.

After that, he then turned his gaze to the trio and the two boys. "You can take her back to the future without worry."

This also marked the end of the Cursed Child prophecy, but in this instance, Erebus knew that the golden trio and their descendants will not remember his presence or his impact on history as Delphi clearly demonstrated. It was intentional on Erebus' part to leave no physical record of his existence in the Wizarding World once he helped young Harry deal with Voldemort.

After all, it was best for him to be the hidden ace in the sleeve that not even the Boy Who Lived knew existed.