i always loved timetravel fics,
but the worst part is usually the either borring, or clishae way they go back in time, buy something in knockturn or steal a timeturner.
having voldemort send him back unintintionally is just awesome:D
that aside i think he has NOT just gone back, but into an alternate timeline. where, aparently his dad does not exist, or is not a prankster.
(he would have been known to everyone, like the weasly twins are. and pranksters usually brand together, they would know eachother.) or gone to an other school. the INCEST line in his head is awesome, and the fight between the sisters is something i HAVE to see/read.
keep it up, and please update soon.