“Hogwarts was the first and best home he had known. He and Voldemort and Snape, the abandoned boys, had all found home here.”

- Deathly Hallows

Tom, Severus and Harry died that day on May 2nd 1998. All three end up having the same grim reaper who explains that much of their life has been orchestrated by the headmaster Albus Dumbledore so that he can claim the Merlin Peverell seat - for the ‘greater good,’ of course. Merlin Peverell had extraordinary magic and the ability to wield dark, neutral and light magic with ease as such had a special role in the wixenaught. He had three sons and divided his estate between the three magic types. The three brothers also created the invisibility cloak (light magic, Harry,) the elder wand (neutral magic, Severus) and the resurrection stone (dark magic, Tom.) Only when the three brothers sit on the Merlin seat will balance be restored to magical Britain. Unfortunately, Albus Dumbledore decided to use his position as headmaster to drive harsh divides between the types of magic and has allowed the orphanage or abandonment of the three boys so that no magic can live whilst only one survives. Lady magic places the three boys in a purgatory classroom where they learn from her grandniece Deþ (death) about their family history and intertwined fates. Then, Tom, Severus and Harry need to decide when they're going back and what they're going to do about the problems they've uncovered. 

Notes

Regarding the timeline, Deþ can either:

•  (1) send them back to May 2nd 1998 to reshape the magical world
• (2) send each back to their own birth time to reshape their world as they grow up with new knowledge

Regarding relationships

• No romantic/sexual pairings between any or all of the three
• Any ‘relationship’ for them to be considered (very distant) cousins or (pseudo-) brothers or grand/parent/child.
• Nothing beyond PG-13 and no relationship age gap greater than: (=half age + 7 years)
• Relationships do not need to be as cannon 
• Abuse of Tom/Severus/Harry by their guardians really doesn’t need to be exaggerated – it’s bad enough as it is in cannon.

Regarding Cannon Plot Issues 

• Why is there a civil WAR if all children go through the same school where teachers could use this time to promote conversation as opposed to cursing/violence? It’s almost as if someone wants all these problems … 

Regarding Plot variances

End Goals

'There is no good or evil, only power and those who use it’ – adapted Philosopher’s Stone 

• The Boys and the wider wizarding world learn about Dumbledore’s machinations
• In this world, Severus can Speak the Ancient and Noble Language of Serpents (*insert preening Snake*) 
• Tom has his soul, body and magic ‘put back together’ and as such is capable of rational thought (happens in the ‘purgatory room’)
• End goal is for them to be politically diverse but otherwise work well together aka no torture or murder (looking at you, Tom.)
• End goal is for them to diversify the student population and types of classes offered at Hogwarts
• Generally improving the culture of tolerance at Hogwarts and thus the whole magical Britian
• A ‘scientific’ explanation for the difference in dark, neutral and light magic 

Little Things 

• There may be another ‘prophecy’ regarding the three boys who will seek to challenge Dumbledore which drives his actions
• If (timeline (2)) Severus doesn't become a teacher, and admits in the purgatory chamber how bad he was at teaching 
• I’d love to see a magical primary school so that muggleborns are brought into the magical world sooner, and a boarding highschool for squibs & non-magical muggleborn siblings so they’re not left out
• I'd love to see muggleborns finding they're related to long-lost squib ancestors - hence the inclusion of non-magical muggleborn siblings 
• Neville may have been the one to kill the Dark Lord Tom Marvolo Riddle after Harry dies
• Their afterlife purgatory room may appear as Hogwarts
• Tom may change his last name to Gaunt, Severus may change his last name to Prince
• They may all be descended from Slytherin but may claim one of the others: Tom - Hufflepuff, Severus - Ravenclaw and Harry - Gryffindor
• Harry may get a pet snake (his ability to Speak is directly from Slytherin – not the horcrux)
• Lots of sneaky snarky Slytherin talk from Severus 
• (Especially (timeline (1)) Pureblood culture should be more similar to Pagan/Wiccan culture  
• The only titles Harry may claim (timeline (1)): Potter, Black, Gryffindor, plus 1/3 of the Merlin seat.
• I’ve always perceived Severus’ love for Lily more like a sister rather than romantic
• If (timeline (1)) Winky and Kreature may have an elfling to call her Dobbie 
• If (timeline (2)) Petunia may have a magical child to call him Aster Black, which is both means flower & star (w/ one of the Black brothers) 
• If (timeline (2)) Severus may have a child to call her Asphodel Eileen Snape with her namesake Lily Evans/Potter becoming her godmother, 

Have fun!