"You don't have anyone here waiting for you to come back, Malfoy. But Blaise does. Every Weasley does, of course. Even Smith has a girlfriend and his brother is also a member of the Resistance. Unlike them, you won't be missed if something bad happens to you, so why risk their lives when I can just take you with me instead? We allow you to hide here with us, so you might as well make yourself useful. This is what I said yesterday and I stand by it."