You're Draco Malfoys' girlfriend, a Slytherin. He's a death eater. Fearing for his safety you decide to join Dumbledore. He led you to the Order of the Phoenix, stationed at Grimmauld Place.

There's a few Hogwarts classmates Harry Potter, Hermione Granger, Ron Weasley, Ginny Weasley, Fred Weasley, and George Weasley. There's also Molly Weasley, Arthur Weasley, Sirius Black, Remus Lupin, and Tonks.

Dumbledore: I've brought a recruit. Please I warn you to keep an open mind. He says before moving aside so the group can see me.

Harry: No. No. Do you know who she is? She's a Slytherin and Draco's girlfriend. She can't be here. She's one of them He says aggravated by my presence.