Professor Dumbledore had to step in after the incident. After all, having a grown man suddenly appear in front of a bunch of kids warrants the attention of the headmaster. Through the use of Veritaserum, they were able to determine the events from 11 years ago. The follow up affairs of getting Sirius Black out of prison seems to be set in motion. Pettigrew would likely be sentenced to Azkaban to suffer death by the Dementor's kiss.
Of course, Dumbledore could have helped Sirius before this fiasco. Dumbledore was the head of the Wizengamot, otherwise known as the Wizard Britain's high court of law. Dumbledore could have insisted Sirius be given a trial to prove what really happened. However, he never did and instead allowed Sirius to be taken straight to prison with no trial. Dumbledore was also the Supreme Mugwump, revealed in Secrets of Dumbledore to essentially be the political leader of the Wizarding World. Even if a trial was undoable, with this position Dumbledore could also have demanded that Sirius be given Veritaserum, the truth potion, so Sirius could explain exactly what happened without the ability to lie.
The most likely reason Dumbledore did not help Sirius is that the result would have interfered with his plans for Harry. Had Sirius not been sent to Azkaban, he would have been Harry's legal guardian instead of the Dursleys. Dumbledore, despite growing to love Harry, was raising him to be a soldier for war and having him grow up in an abusive home with the Dursleys would ensure Harry would be more vulnerable to Dumbledore's manipulation as Hogwarts would be Harry's first loving home.
Just like this, I had gotten back my godfather and Pettigrew would not be in the position to help Voldermort. Step one of the plans completed.
Ron was in a state of shock after the incident. Well, taking care of a grown man as a pet for so many years... It's probably going to leave a scar. The Boy-who-lived-with-a-grown-man? It was pretty traumatising for him. His brothers had to console him when they found out about it. Of course, Percy was also blamed for bringing the rat home.
…
Classes continued after that. Next up was potions.
Professor Snape came brisk walking into the room. Without any introduction, he started his lecture.
"There will be no wand waving or silly incantations in this class. As such, I don't expect many of you to appreciate the subtle science and exact art that is potion-making. However, for those select few who posses the predisposition… I can teach you how to bewitch the mind… and ensnare the senses. I can tell you how to bottle fame, brew glory and even put a stopper in death."
He made eye contact with me at that moment.
"Mister Potter, our new celebrity. Solving a decade old case on his first day. How about your Potions skills...? Potter! Tell me..., what would I get if I added powdered root of asphodel to an infusion of wormwood?"
"A sleeping potion so powerful that it is known as the Draught of Living Death… Sir", I said calmly.
From the numerous books that I have read so far, based on the Victorian Flower Language, wormwood means 'absence' and also typically symbolised bitter sorrow while asphodel is a type of lily which symbolises 'Regrets for the death'. Together, it could be expressing Snape's regret for not being there when Lily died. This guy is still a simp for my mother after all these years…
"Hmm..., where, Mr Potter, would you look if I asked you to find a bezoar?", Snape continued.
"It can be found from the stomach of a goat and it will save you from most poisons… Sir", I replied.
"What is difference between monkshood and wolfsbane?"
"They are the same plant, which also goes by the name of aconite… Sir".
…
We continued this game of twenty questions until he started asking the curriculum from the second year. I hadn't read that far.
"… I don't know… Sir", I said, knowing that he would have kept it up even if I knew the answer.
"Pity, clearly, fame isn't everything. Is it, Mr Potter", Snape said. He continued with his introduction of the subject of Potions and made it a point to deduct points from me whenever he had the chance. And I, made it a point to visit the library that day to brush up on my lack of knowledge. I wonder if the Room of Requirements could bring me books too. I need a place to practice making potions as well. It seems potions making isn't as simple as a chemistry experiment, I probably need to brush up on Herbology too.
I understand that my father, James Potter, was probably a bully to him during the school years and this is him taking his revenge. Well, I'm not going to get between this weird love triangle. All three of them were all in the wrong. Anyways, both my parents are dead and there isn't anything to do. James was a bully as a kid, but Snape is a bully as an adult. And during his school years, he began to involve himself in the Dark Arts.
Ultimately, it was Snape's decision to join the Death Eaters. It took Lily Potter's death for him to actually ditch the Death Eaters. He should have switched sides because their cause was morally abhorrent, not because he personally lost something as a result of their actions. I wonder how many people he actually had killed too, directly or indirectly.
Also, he was totally fine with Voldemort murdering a baby. He begged Voldemort to spare Lily's life, but he had no moral issue with Voldemort murdering her husband and her son, me. And I take offense to that.
Potions master? That's easy, I'll put that on my to-do-list.