Professor Quirrell was demonstrating the unforgivable curse, when he has said everyone hit by the killing curse had died, except for Harry Potter.
When he said Harry name a invisible dome appeared around him as Professor Wuirell aimed his wand at Harry and said," AVADA Kedavra" and the killing curse hit the dome which became visible, the color of gold and the curse rebounded off the golden dome and hit Quieell and vaporized him. Voldemort was possessing him and he head burnt out of Quirells body, screaming". Why won't the killing curse kill you!!" Then he drifted they the outer wall, where a dementor was cruising accidentally and sucked up Voldemort's spirit.
Then the dementor sneezed and Voldemort got halfway out, but the dementor inhaled quickly and sucked him back in.
All of those kids who followed the dark lord turns casting the killing curse at Harry or other griffendorks. Harry remained untouched, but the curse rebounded off of him and killed all those who tried killing him.
Sad to say Ron Weadely was amongst the dead of Griffendork as was Draco Malfoy of Slythendork along with the Nott and Parkinson's families as well.
Harry was notified by owl from the goblins he had inherited the vault contents of the Malfoy, Parkinson and Nott families since he ended their lines.
Quirells lines was dead as well and so did on Thomas Riddle finally be listed as dead. So Harry also inherited those monies as well.
Anyways the next few years at school Harry did quite well with Hermione Granger tutoring him along the way. They both graduated top of their class and went into the muggle world to do most of their business and made millions.
20 years later Harry & Hermiones twins, Garry and Larry we to to Hogwarts. Each year there after the girls, then the boys and then the girls kept coming to Hogwarts.
There were the first two; Garry & Larry, then Becky & Mecky, then Harold and Ronald, then Nancy & Fancy, then a few years went by and there was the last few: Barry, Harry, & Karry.
Meanwhile Albus Dumbledore had a breakdown, mentally when he figured out that Voldemort was gone for good and was not coming back.
He even tried manipulating Harry, but Hermione intervened. She let Dumbledore see the rune chain etched into Harry's forehead that whomever mentions a killing curse, the golden dome draws energy from the next caster of the unforgivable killing curse, and essentially guarantees the curse will rebound and kill them.
Albus can hardly believe it and Hermione tells him to calm down she would see to it Harry was taken care of. Albus whipped his wand out and tried to use that curse and his wand flew out of his hands.
Albus retired that summer into oblivion. Harry and Hermione went onward making piles and piles and tons of money.