The original story was written by J. K. Rowling. My story is mainly about Severus Snape.
Severus Snape is two years older than in cannon, which means Lily, James, Remus and Sirius are two years younger than him. Amelia Bones is one year older than Severus. Severus started going at Hogwarts during 1974 years. Severus, despite his half-blood heritage, is at the top of hierarchy and is very brilliant. He creates and modifies potions, creates new spells.
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Prologue
1977 October
Severus was slowly walking to the library, when he heard a few whimpers. Walking faster he rounded the corner and saw a girl struggling against two Slytherins and three Gryffindors. Severus immediately pulled out his wand and hexed two of the boys. Others looked around and after spotting him fled. He slowly walked near the girl, still having his wand raised just in case. He recognised the girl as a fifth year Hufflepuff Bones. Her clothes were damaged, but her attackers obviously hadn't ripped all of them apart yet.
The Hufflepuff was already standing. Severus wasn't all that much surprised. Most students knew that Bones was going to be an Auror. Being tough was probably one of the requirements. Still, after such attack he didn't think it wise to leave her alone so suggested going to the kitchens.
Amelia hadn't really known the slightly younger student, but had heard him being referred as a prodigy. Looking at him she just had to agree. He hadn't been even the slightest nervous about hexing multiple opponents. She wasn't sure whether or not he was trustworthy, but was pretty sure that she won't be attacked by him while going to the kitchens.
"Alright." she agreed.
1974 Autumn
From his very first day at Hogwarts Severus Snape was noticed by his teachers and students alike. One just couldn't compete with him. Whatever was asked of him, he managed to answer and what he didn't know he could figure out all too quickly. His teachers couldn't not notice that deep understanding of magic Severus had.
Filius Flitwick, the head of House Ravenclaw, was contemplating the character of a young Slytherin, who currently was busy breaking all disciplines records except Herbalogy, at which he wasn't extraordinary, but just highly educated since he didn't have green thumbs, though still got Outstanding marks.
'Obviously, the young Snape is very ambitious individual as it seems he seeks to the best at many disciplines of magic. Probably, very cunning too. It 's a pity he hadn't gone to my house.' mused the Ravenclaw Head. 'I suppose I might have to invite Mr. Snape-Prince to a dueling circuit as it would be very beneficial for his reflexes and magical skills.'