Ginny Weasley had felt a lot of regret and a lot of guilt in her short lifetime. She had practically drowned in it after being possessed by Tom Riddle in her first year. But as she got older, and, as she liked to think, wiser, she had come to realize a few things. One, regrets are pointless. It's too late to change whatever you did wrong, so recognize your mistake, make sure that you've learned from it, and move on. Two, some things just aren't under your control. So, instead of feeling guilty, take charge and assert control over the situation. And third, if it was your fault, instead of wallowing in guilt about it, take corrective action.
Although nobody had ever really blamed Ginny for what happened with Tom Riddle, Ginny knew that she was at least partly responsible. There had been many times when she had thought about telling somebody about the odd nature of her diary, and the fact that she never did had been a source of much private shame and guilt. But, the true wrongdoer had been Riddle. Although Ginny had had a part in the whole affair she had ultimately decided to let all of her self loathing feelings go and instead focus on what she could do to make herself a more valuable witch in the fight to defeat Voldemort.
Still, Ginny couldn't help but feel a little guilty that she had wormed her way out of helping to clean the attic. Whatever had happened to her brothers, Tonks, and Hermione; she should have been there too. Because they were her family, all of them, and family stick together to the end. So instead of letting the guilt set in or getting caught up in imagining all the bad things that could have befallen them, she decided to do something about it. She was going to figure out where they were and she was going to get them back.
Arthur Weasley was worried. Two of his children, another he felt for as if she were his own, and an important order member were missing. Not only were they missing, but they were missing from a supposedly secure location where one of his other children still resided. He had wanted to immediately evacuate Molly and Ginny. Typically, neither would hear of it and Dumbledore's message that everyone should sit tight until he got there had effectively squashed the notion. So, they stayed and waited, hoping Dumbledore would be able to fix everything when he got there.
In the meantime about a dozen order members had arrived. Bill, Remus, and Kingsley had headed up to the attic to search for any spells or enchantments that may have played a part in his children's disappearment. Everyone else sat at the kitchen table or stood around whispering forlornly while shooting glances at he and Molly. They were acting as if his children were already dead!
The thought made him search for Ginny in the crow. Tto make sure that at least one child was safe. But she was not in the kitchen. He started to feel physically nauseous. He had specifically told her not to leave the kitchen!
Arthur found himself running from room to room frantically yelling for Ginny. She couldn't be gone too, she had to be safe. Finally, panting, he came to the attic and was relieved to found not one, but four heads of red hair beckoning him from the other side of the attic.
Arthur had no doubt that the twins had convinced Ginny to come up there with them when they had somehow arrived without his detecting them. And although Arthur usually left all the disciplining and yelling to Molly, the twins were going to get an ear full from him later that night.
However, there were more important things for him to worry about at the moment. Such as what everyone were yelling about in the far corner.
"…But Ginny how would you explain the footprints leading away from the mirror?"
"Look at them. There's no way any of those are Ron or Charlie's prints. I bet even Tonk's feet aren't that small. Hermione was probably over here and walked away at some point before coming back. Don't you think it's a little suspicious that all their footprints come this way and suddenly stop? They went through that mirror!"
"Although I admit that there are a small number of mirrors out there that can transport objects to another location," Lupin spoke, "We would be able to detect the spells that the mirror works under and even Bill can't find anything."
"Plus," Bill piped in; "these types of mirrors usually have a special spell that basically turns them on. There's no way any of them could have cast an intricate, specific spell that none of them could even know by accident."
"I don't care. I know that this is it, I can feel it. And I will figure out what this mirror is if I have to read every book in Hogwarts!"
"I sincerely doubt that that will be necessary Ms. Weasley."
Arthur was shocked to find Albus Dumbledore standing right next to him. He hadn't even noticed the powerful wizard's arrival.
"It would also be a futile search. You will find nothing about that specific mirror in the Hogwart's library."
"So you know what it is?" Ginny asked eagerly, "What did it do to them, are they okay?"
"I believe that they will be able to sufficiently fend for themselves where it has taken them."
"Well," Fred and George said at the same time, "Where are they?"
"That," Dumbledore replied gravely, "will take some time to explain. Perhaps we should return to the kitchen where we will be more comfortable. The history of this mirror is not a short one."