Warning: This story contains romantic love between siblings, if you don't want to read about that, please read something else.
James and Lily Potter had a good life, they had two good children, they earned enough money to get by and still have a little left to use for fun activities. There were just one thing that prevented them from calling their life perfect; their children hated each that is no exaggeration either, they absolutely loathed each other. No-one could remember why, not even the children themselves.
The children were twins, Harry and Rose. During the first couple of years they looked so alike that almost everyone kept mistaking one for the other. Their interests were very much the same, neither liked quidditch, despite their dad loving it, both could spend hours quiet just reading, whether it was muggle fiction or dry treaties on esoteric and ancient magic.
Their hatred went so far that several times they had injured the other severely, they even had gotten close to killing one another a couple of times.
During the latest time that they had attacked each other and lay unconscious in their beds after being patched up as good as they could Lily and James sat down to talk.
"We have to do something about this, if we let it go on then one out the other is going to hurt the other in a way that we can't fix and we can't afford to go to St. Mungo's any more to fix them up. What can we do?"James asked his wife.
"I've been thinking of it for some time, and the only solution I can think of is to implant a suggestion that they love each other." Lily held up her hand to stop her husband from saying anything, "I know what the mind healer said, that such suggestions can cause problems down the line if you are not very careful... But I can't see any other options. I have thought on this for a long time and I have come up with a suggestion that can't possibly do anything bad. We just give the suggestion 'love your brother/sister.' Can you see anything that could go wrong with this?"
"I can't see anything, but should we not have a mind healer do that? Just in case?"
"You remember as well as I do when we went to them last year, we used up our last savings and the did nothing to help, they just said it was a phase and would solve itself shortly. It would take years to save up enough to go to them again and we have no guarantees that they would actually do anything this time. Also, they start Hogwarts in just a couple of months, you know how dangerous it would be if they are still like this and we can't watch over them."
By the time summer was coming to an end Harry and Rose were able to sit and eat dinner at the same time without coming to blows and their parents had never been happier. With the great change in how the children acted it was only a moderate surprise to their parents when they came together to ask to go to Flourish and Blotts to get some extra books.
When on the way home the twins started arguing about one of the new books James and Lily was just about to dive in and separate them before they could do too much damage to one another when they noticed that the argument was held at conversational tone and was not the high pitched screaming matches they were so used to.
While the parents knew that their children were smart, it had never sunk in really how smart they really were, so when they stood back to listen to the argument they found that it flew way over their heads. James and Lily were both in the top ten percent of their year in school, but neither had been all that interested in studying magic past the NEWTs and had always been happy with just what they learnt in the classes in school and was always better with the practical application than the theory.
When they then heard their children discussing theoretical applications of charms in matter transfigurations all they could do was smile at each other and be happy they had such smart kids.
September first arrived and the whole family apparated onto platform 9 and 3/4. The twins boarded the train just minutes before it was set to leave and Lily could not help the tears of happiness the sprung in her eyes at seeing her once so antagonistic children actually helping each other get the school trunks onto the train.
The summer after the twins first year of school arrived in an hurry, Harry and Rose had chosen to stay in school over Christmas break to be able to study more in the famed library of Hogwarts.
After a short vacation with the whole family the elder Potters went back to their fulltime work that they were able to start after the twins went to work, before that they could not keep more than halftime because they always had to be present to keep the children from killing each other, thus leaving the twins mostly alone.
According to the report cards from school the twins were shared first place among the first year students, even the studious Hermione were unable to keep up with them.
During summer after second year the twins would constantly hold hands with their fingers entwined, even going so far that Harry had started eating with his left hand so that they would not have to let go off the other's hands even then.
Their parents when they saw this where just happy that the twins got along so well, not thinking much about it.
After their third year at Hogwarts they could be seen kissing, lips to lips, as often as they could get a chance for it. When they thought that no-one was watching they would even kiss with their tongues.
When their parents noticed this they went to their study to discuss it. After some discussion they decided that this was nothing to be worried about, that it was just normal behavior between overly affectionate siblings.
During the summer after Harry's and Rose's fourth year at school they discovered that their children would sneak into the others room every night, but when they went to tell them that they could not do that, James and Lily saw just how cute they were just cuddling together in the bed, and as they both were wearing pajamas they decided to not say anything. They rationalized that the twins were not really doing anything inappropriate, and they did not want everything to go back to how it was before.
The next summer they could not delude themselves anymore, as they were picking the twins up at the Hogwarts express, they came upon them sharing a passionate French kiss that went on for minutes. The parents after seeing that were about to call the two kids in for an intervention, but as they calmed down and didn't do any such passionate displays of affection after, they decided to wait.
A couple of weeks later, after their OWLS had arrived, the twins disappeared from the house for a whole day, something that they had never done before. The next thing that their parents saw of them was when they were lying in the same bed naked, sweaty and exhausted, yet somehow glowing with happiness.
Getting the twins to get out of bed and dressed after that was hard, but James and Lily knew that they needed to have a serious discussion with the twins.
When the entire family were seated around the living room table, James demanded, practically shouting, "How could you two do that? You are siblings, even worse, you are twins!"
"We did this because we love each other." Harry said as Rose nodded, "we have been in love for years now, and as we have taken our OWLS we can legally marry." With that they both held up their left hands to show off the simple gold wedding bands that circled around their ring fingers.
"We got married yesterday, I would have loved for you two to have been there, but we knew that you would have tried to stop us." Rose explained.
"No, that can't be, you don't love each other! We put a compulsion on you a couple of months before you first went to Hogwarts!" Lily exclaimed.
Harry shook his head, "Did you really think that we would not notice the compulsion? We've known about it since half way through our second year and we removed it during our third. The compulsion did exactly what you wanted it to, it just got us to stop trying to kill each other, the rest was all us." He stops to kiss his wife, Rose.