#1 Adopted by Trinjo1176
Harry bumps into Draco while they're going to opposite classes and all their things fall on the floor. They pick them up, but Harry accidentally takes one of Draco's notebooks. He pulls it out of his bag later that day, opens it and sees little Potter scribbles all over the margins.
#2 - Adopted by DrarryCrazyCermet
Harry and Draco get stuck in the ministry elevator.
And not only once -- or twice.
If they work there, are in a friendly relationship or still enemies is up to you!