I figure once the ice was broken with the newspaper, the pairs would start to work more closely together (H&H and D&L). Harry and Hermione would be close already thanks to their history, and while Draco doesn't have any friends, I would think Luna is still a bit of an outcast, it's not a stretch to give them a nudge to befriend one in another. Unless you're thinking about actual specific interactions, we would need to talk further about what they would actually do, yeah.