Draco:
You'd been spending time in the muggle world with your family when you found out you'd been expelled, Draco had come to see you since it was the last week before you all headed back to Hogwarts, Draco was getting to know your sister when it happened. It came out of no where but three armed wizards came out of no where and began to attack people in your family, you panicked reaching for your wand and shooting off spells. Of course this ended up leading to you being expelled even though you were defending your family, your trail wasn't fair and no one was allowed to testify on your behalf
Fred:
It wasn't really a surprise when it happened, Umbridge found out you had helped the twins with their spectacular exit and that was the last straw, she'd been looking for an excuse to have you out of the school from the moment she got there, you hated her and she hated you, plain and simple. You were sad to leave but at the same time you saw it as an opportunity to grow as a person, Fred and George had already promised you a job at their place since you were dating Fred, but you told them it would be until you got on your feet and got what you wanted to do, you loved them both but a joke shop wasn't your dream job
George:
You'd been on the pitch when Malfoy was bragging about the Weasley is our king song, you'd tried to calm George down but when they mentioned his mother you lost it, she was the most kind woman you'd ever met in your life and you pounced at Draco, knocking him to the ground and began to punch him in the face, hitting him a lot in the nose and you were sure you'd broken it, or broken your knuckles, you pulled off him by Fred and George but you slipped out of them aiming your wand and shooting off a charm that gave Draco a bunch of boles all over his face.
Harry:
You'd been with him when the Dementors attacked him and Dudley, you'd been walking further behind because you wanted to catch up with an old friend but when the sky turned grey and cold you knew exactly what was happening, you rushed to Harry's side ready to aide him in anyway you could, you knew the spell, you knew how to do it but you couldn't preform a full patronus yet, that was until you'd seen Harry on the floor, you'd managed to do it and get them off him and his cousin. While Harry got a fairly fair trail you were told you had no right to be there, and there was no reason Harry couldn't have handled the situation alone and didn't need a second Wizard preforming underage magic, you were expelled.
Ron:
It was a couple of things that led to you being expelled, first you began bewitching Draco's wand whenever he would be playing against Ron so that they had a fair fighting chance, then you began letting niffler's into Umbridge's office with Lee, you took the blame of course because that's what you did. Then the final straw was you flying around the castle on your broom after Fred and George had made their exits, Ron had asked you not to but you wanted to be included in the fun, it had been a while since you'd gotten to fly, and it felt amazing up until you were caught by Umbridge and brought down to the ground.
Neville:
PDA was one of Umbridge's rules, you knew this but you didn't care. You wanted to hold your boyfriends hand, kiss and hug him whenever you wanted to without some old hag having a go at you just because she was lonely and miserable. You were hidden in the back of the library with Neville going over some homework when you heard the tapping of someones foot, you looked up to see Umbridge standing there, hand on her hips. You were sitting on Neville's lap which she clearly didn't like, she took your to detention and you began writing out lines, you'd done it before but this really ticked you off tonight. She was having you write that you were promiscuous over and over again and you'd had enough, you threw the Quill into the fire and stormed out of the office.
"You take one more step and you're expelled from this school!" You turned to look at the old witch with a B and shook your head.
"Fine by me!" You yelled, jogging towards the Common room to get your stuff together