Note: Okay, so I'm not gonna promise this'll make sense, because this is what happens at 4AM when I can't sleep, and generally, I'm not thinking coherently.
Disclaimer: Yeah, yeah, you know the drill. I don't own anything related to Harry Potter, etc. and I'm kind of glad I don't, because if I did, it would all be like this and no one would understand it.
After Everything
After the Battle of Hogwarts, the trio went back to complete their seventh year at the school. Hermione because she felt incomplete without all seven years behind her, Ron because after everything, he would never leave Hermione again, and Harry because after the other two bad risked everything for him, he wasn't about to leave them to fend for themselves for a year, and, well, Hogwarts was his home.
After the war was over, and then later after their official seventh year, eventually the trio and Ginny lived together for years.
Ron had originally gone back to live with his family, Hermione had tracked down her parents and carefully undone the memory charm she had placed on them and lived with them in their old house, and Harry lived alone, first in Shell Cottage and eventually in a small house next to the one his parents had been murdered in. They tried to stay like that for a while, Ron and Hermione, Harry and Ginny trying to take their relationships slow, because, after all, they were still young, and for the first time since they arrived at Platform 9 3/4 to start their first year at Hogwarts, they knew they were safe.
But in the end, it didn't work. Each of them was haunted by the war in their own way. Not just the Final Battle, because to them, the entirety of their time at Hogwarts was a war - it was both the best and worst time of their lives. In the end, not one of them could bear to live alone, they could not bear to sleep alone. They each thought they were alone in this until one night when they decided to all stay at the Weasley's for old times sake.
Harry stayed with Ron in his room and Hermione with Ginny. Secretly, each of them was beyond happy that for once, they were not alone, but pride got in the way and they refused to say how at home it made them feel.
When it was way past midnight and they were drifting off standing up, the girls left Ron's room where they had been sitting on the floor with the boys telling stories of their new lives. They trudged back to Ginny's room, leaving the boys to crawl in their own beds and slowly drift into unconsciousness.
Harry started the night off better than ever, thinking being with his best mate would help keep the dreams away - but he woke shaking, covered in sweat after seeing both the too familiar flash of green heading towards him from the wand of Voldemort himself and the picture of Ginny's body cold and almost lifeless on the floor of the Chamber of Secrets. When he woke, he saw Ginny standing over Ron - she was crying, trying to wake him because in the next room Hermione was screaming in her sleep. When Ron woke up he was shaking as well and as soon as he figured out what Ginny was crying about he bolted out of bed and ran to her room. Harry then went over to Ginny and wrapped his arms around her and pulled her into his bed, calming both of them.
In the other room, Ron had gotten to Hermione and was shaking her awake, tears streaming down his face onto her and into her hair because every night he was tortured by Hermione's screams and standing over her trying to wake her was his worst nightmare, only a million times worse because it was actually happening.
Behind Hermione's eyes flashed images of Harry's limp body in Hagrid's arms, the yellow eyes of the Basilisk in her hand mirror, Bellatrix's face hovering over hers, Dobby's body covered in blood in Harry's arms, Ron covered in blood after being splinched, Ron making out with Lavender, Ron yelling at her and walking out on them in the forest... Finally she woke with a start to find Ron over her. She arched her back up so she could wrap her arms around Ron's shaking frame. She kissed his cheek and whispered in his ear it's okay over and over. His body eventually stopped shaking and so did hers. Once they could both breathe again, Ron collapsed on the bed next to Hermione, wrapping his arms around her.
In the morning when Ron and Hermione woke up, Harry and Ginny were in the bed next to them in a similar position.
That's when they each finally accepted that they had to stay together. They were the only ones who knew what it was like, and they were the only ones who could comfort each other. When they decided to move into Harry's house in Godric's Hollow it first was going to be just the three of them, but at the last minute Harry stood up and announced that Ginny would join them. He remembered all those nights when Ron and Hermione had fallen asleep holding hands or accidentally fallen into each other in their sleep - he remembered how lonely he had been seeing them together all those times. It was so obvious they were in love, even then, even if they wouldn't admit it. So Harry needed to have Ginny with him. Ron and Hermiome were fine with it because they remembered the nights that Harry had mysteriously disappeared being correlated with the nights they accidentally showed affection for each other. They knew that Harry needed Ginny as much as they needed each other, and that Ginny would be able to help Harry just as much as they would if not more at times.
So they moved. At first it felt weird, as if they were off camping, tracking down the darkest wizard of their time. But eventually they got used to it, fell into a routine, it became more natural for the four of them to be together than apart.
And eventually... All was well.