Flowers and Light

Zack and Aerith had been hanging out in Aerith's church, admiring the flowers. Zack had come back from a long mission as 1st Class. All is well when a bright and blinding light envelopes the two and lands them in 12 Grimmauld Place in front of people they don't know but claim to know who they were. What happens when the two are still forced to go to Hogwarts, despite being far older than all of the students, only to come across the infamous pink toad of the ministry?