Fred and George had always felt more protective of their only sister than the rest of their brothers seemed to be. Bill was off at Hogwarts before she was even born, and Egypt after that; similarly, Charlie was off in Romania pursuing his love of dragons; Percy had always struggled with caring about anything more than what book to shove his nose into that day; and Ron was too close in age to see she needed his protection. So that left Fred and George to be there for her, when all her other brothers were preoccupied. And lucky her, they reminded her constantly, that she had the best of her brothers looking out for her.
When she was the last to be left home when they were at Hogwarts, they wrote to her everyday they were away. They regaled her with stories pranking with their friends, of Ron and Harry and eventually Hermione, of bothering Filch and Peeves. It became a routine, after classes and before dinner they would steal away to the Owlery to send off their letter with one of the school owls. Her reply would come back a couple of days later, with more questions about the teachers, about how McGonagall could transform into a cat, and the half giant Games Keeper Hagrid who lived on the grounds.
When she began her first year, it was Fred and George who congratulated her when she was named a Gryffindor, Fred and George she sat next to on that first night in the Great Hall. It was they who wrote home immediately to their parents with excitement. On the first Hogsmeade weekend of the year, they used the money the had pooled together in a bet against Lee Jordan to buy her a block of Honeydukes finest. When the first negative effects of the diary began to show themselves, it was Fred and George who commandeered the comfiest chair in Gryffindor common room in order to comfort her.
At the beginning of their fifth year and Ginny's second when the Hogwarts Express was attacked by dementors, Fred and George found her in a compartment with Colin Creevey and Luna Lovegood and made sure she was okay. They transfigured a couple of jumpers into large blankets and set up a fort for the fivesome, so they would be warm on the rest of their way to Hogwarts. The night Sirius Black scared the fat lady from her portrait and Gryffindor was made to sleep in the Great Hall, Fred and George made sure they slept either side of her.
In her third year, when Harry's name appeared from the Goblet of Fire, she turned first to Fred and George. She had well grown out of her crush by then, but he was still all of their friend. In a way that only Fred and George could carry out, they joked with Ginny about the severity of the tasks so much so that they took bets on the outcome. Whilst they knew Ginny wasn't fooled, it took her mind off it and made her laugh. They had a strong belief that laughter was the best medicine, and it had always cured any problem Ginny had brought to them.
In their seventh year, the world started to turn upside down. Ginny was the first person they shared their plans for what would one day be Weasley's Wizard Wheezes. She was one of the first to trial their earliest prototypes for their Skiving Snackboxes (a favour they would pay her back in kind with a portion of the shop in her name). When the school year began, they noticed she had begun to date. She didn't come to them with this, and it was something that troubled them for some time (A. Because how were they supposed to keep an eye on her and make sure she didn't get hurt? B. because it meant she no longer needed them as much as she had in the past). Then Dumbledore's Army was created, and Ginny showed them she truly didn't need them to make sure she didn't get hurt. Perhaps the most shocking thing to come out of that year, was that Ginny had kept her Quidditch prowess a secret from them.
Their first year out of Hogwarts was one of the hardest they had faced yet. They wrote to Ginny everyday, much the same as the year before her first year at Hogwarts. She confided in them about her fears for the changing world around them, about feeling bad for getting worked up over trivial things like fights with Dean. Their response to that letter was to break up with him of course, to which she replied with a crude drawing of a rude hand gesture. They responded with a package of one of their most recent creations at the time: Self-Propelling Custard Tarts. Ginny used these on Ron to break up a snogging session with Lavender at breakfast one morning, and Fred and George enjoyed her recount of it immensely. She conveniently left out that she began to date Harry, and whilst they weren't bothered in the slightest, it was fun to to pretend they were.
The more the war progressed, the more unpredictable their lives became. When George returned from the battle of the seven Potters sans an ear, Ginny and Fred were the first by his side. Ginny held a cloth to his ear, tear tracks staining her face, whilst Fred tried to gauge the severity of the situation. True to his character, George played it down with a joke. She wasn't fooled when she was thirteen, and she wasn't fooled now. When Bill's wedding was attacked, Fred and George found Ginny and apparated. It was the three of them again, and all three were terrified but they had each other. They were by the seaside, near a cottage they had vacationed at before when they were younger. They felt safe. They went underground for a couple of days before joining the rest of their family back at the Burrow.
Ginny went off to Hogwarts for her sixth year. Letters were few and far between, what with the post not being secure. The hardest year for them yet. Fred joined Lee Jordan on Potterwatch, and George let everyone in Dumbledore's Army know the password using their membership coins. They knew Ginny was listening. When news got out of students breaking into the Headmaster's office to steal Gryffindor's sword the twins were worried. Ginny had more than proven she could hold her own over the years, but they were supposed to be there for each other. After almost twelve months of them being missing, Harry, Ron and Hermione came back to Hogwarts. Ginny let the twins know, and they in turn alerted the Order. The Battle was a mess; Fred and George were hurling hexes, flinging jinxes and casting curses at so many people, trying to keep each other and their sister in their peripheral vision to make sure they were okay. Neither George nor Ginny were by Fred's side when he was struck with the killing curse. It was only when they entered the Great Hall during the ceasefire that they found out.
George was floored; he could barely stand, his vision blurred and he felt faint. Ginny had to hold him up so that they could make their way to Fred's lifeless body. George collapsed beside his twin and Ginny was there, holding them both, tears raining down her face this time. George needed her this time, he needed his younger sister and it's not something he ever thought would happen. George's heart ached as he felt a piece of himself disappear.
Ginny did her best to be there for George to pick up the pieces. Ron helped him with the shop, but Ginny was there for him to lean on, like Fred and George had been for her for so many years. If they weren't in each other's company they wrote to each other. Slowly, they mended each other. Fred shared with her every moment with Angelina; his worries about telling her how he felt, their first date, how that first date made him feel, how she made him feel. Slowly, slowly. Fred and George were always there for their baby sister, and Ginny would always be there for them.