There's an empty place in Harry's mind where Voldemort used to be, an easing of pressure he hadn't known was there until relief came, because though there had been moments when he'd been all too aware of that presence (exploding pain and memories that weren't his and a language he shouldn't know and sometimes this bitterangerhatelustresentmentfury that drove out all thought of happiness just as surely as a Dementor ever could), the everydayness of it had been as easy to ignore as background static and now the silence rings so loud that it hurts his ears.
There are empty spaces in the conversations Hermione tries to have with her parents, things she can't possibly explain (years she can't put into words, when the time she spent with them was like a timeout in a Quidditch match, and if she can't even explain Quidditch to them, for God's sake, how could they begin to wrap their minds around the things she's experienced?), and the thought of trying is almost as painful as the knowledge that they'll never understand who she's become.
There's an empty chair at the kitchen table in the house Ron has always called home, and the pain clamps around his chest when someone starts to say 'the twins' or 'Fred-and-George,' and even though he had sort of always knew that there was no way his family would make it through it all intact (it was a statistical impossibility, Hermione might say, with his family being as large as it is and its members being the way that they are--there's a reason the Weasleys are always sorted into Gryffindor) there had been a part of him that expected that he would be the one to fall, and sometimes he thinks it would have been easier if he had been.