Year 1
It was the second week on a Tuesday at 19:00 they finally met. Even though Rose was sure he didn't know who she was, he still seemed to be avoiding her. However, the circumstances under which they met were rather embarrassing – for her at least. She was briskly walking to the Library with her books (all 5 of them) when she collided with something definitely body-shaped. All her books and herself went flying.
She landed somewhat spectacularly on her – well for lack of a better word – bum.
Towering above her was the face she longed to look at her. But what came from his mouth was most certainly different to what she imagined. It went like this: 'Red hair and hand-me-down robes. You must be a Weasley.'
Rose 0: Scorpius 1.
But to his complete surprise she replied: 'Blonde hair and a constant sneer. You must be a Malfoy.'
Rose 1: Scorpius 1.
She picked herself up and gathered her books with as much dignity as she could muster and entered the Library without a second look at him. He was still staring at her with a very shocked look on his face.
Rose 2: Scorpius 1.
The next day Rose was in the Library again when she heard an agitated muttering from behind the bookshelf she was currently looking at. She peered through a gap and saw Scorpius struggling with a DADA question. She made to go over and help him but stopped and remembered what her father said to her before she left: 'Make sure to beat him in every test Rosie.' Where was her Gryffindor courage when she needed it?
Oh, screw it.
She took bold steps and sat next to him at the table. He looked up. She read the question he was stuck on. It was 'What dark creature has brittle fingers, so you must break its grasp to escape?' He still looked perplexed. She carefully wrote 'Grindylows' on a piece of scrap paper and walked away.
This is how they became friends.