Charles & Harry Potter are born twins, and both are eligible targets for the prophecy. Worried about the continuance of the Potter line (and the family duty as keeper of the Hallows), James convinces Lily that they should split up, so that if there is a betrayal, at least one child will survive. James takes Charles to Potter Manor, and has Lily take Harry to Godric's Hollow. Dumbledore casts the Fidelius on both locations, and has Lily and James be each other's secret keeper.
Dumbledore finds out about the Deathly Hallows, and covets them, both for their power and as a tribute to his fallen comrade, Grindelwald. Dumbledore betrays the Longbottoms, and since the Fidelius was unable to completely erase the memory of Potter Manor, he tells Snape to help Voldemort find his way in. Voldemort then defeats James, and attempts to murder Charlus (Charles) before the eyes of his father. The spell backfires, with Charles becoming the Boy-Who-Lived, unwittingly demolishing Dumbledore plots for the Hallows. James claims victory over Voldemort, which rockets him to control of the Wizengamot (Dumble maintaining his position in the ICW), and never releases control of his cloak.
The attack on Potter Manor happened five years after the Prophecy was made, rendering the twins nearly 6 when it happened. A failed-attempt on Godric's Hollow sent Lily and Harry into hiding in the Welsh countryside, after Lily planted evidence of their demise. She finds out about the attack, and the family is reunited. The estranged brothers remain estranged, but respectful of family. Charles is a Gryffindor w/ Hufflepuff sentimentality and Harry is a Ravenclaw with Slytherin tendencies.
The Elder Wand left the control of the Longbottom family many times, but somehow always makes its' way back. Grindelwald-in his youth-defeated Llywelyn Longbottom (husband of Augusta) for control of the Deathstick; which was then won by Dumbledore. Neville knows nothing of it because his Grandmother-who raised him-was not born a Longbottom, and knows nothing of the family's secret role in British history. He does feel a certain animosity towards Dumbledore, and tirelessly prepares himself to reclaim his family's honor.
The Gaunt family had more than one branch, and Voldemort wasn't the end of it. The reasons for this are two. 1. Merope's Grandmother had a sister who married an aristocrat named Greengrass, and 2. Tom Marvollo Riddle had children. Only one of them legitimate, but children nevertheless.
Voldemort wasn't megalomaniacal, but still sought after power and immortality, and given the historical role of his family, it is kind of justified. He tried to unite all three Hallows as well, but he wasn't the Horcrux-creating monster who cruciated his followers on a whim. Yes, he tried to kill a child, but that was due to the madness that ill-understood prophecy brings about (even though the prophecy was faked by Dumbledore in an attempt to end the Potter and Longbottom lines and claim their Hallows). Voldemort is dead after the attack on Potter Manor, but can the family of the Resurrection Stone ever truly be gone? (He could be a guiding "angel" to his daughter).
The story involves a power struggle between the descendants of the brothers Peverell, who include: a rising Lady Necromancer (daughter of Voldemort), a shy/brash Longbottom, the rival Potter twins, and a united sisterhood of Greengrass girls.
The story follows Harry, who will have multiple relationships, while dealing with the stress of grades, being the brother of the BWL, and a child of parents who were apart for too long. He will be a pawn, then a player in the brutally-manipulative games of Dumbledore, Voldemort throwbacks, Ministry incompetents, international incidents, and a rising darkness that would haunt the nightmares of Voldemort's twisted imagination, all the while figuring out the history of his ancestors and the game of Hallows politics that will determine the destiny of magic in Britain for a thousand years.
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Wales
Harry doesn't hate his family. He has a healthy respect for his brother (due to abilities and grace), but not much affection. Harry supports him as a Potter and a Welshman, but passively. The Potter family is Welsh, so they have Welsh names, but use standard spelling in the wizarding world. Thus, Harry is Hywel and Charles is Siarl, James is Siams, and Lily's name is the same in Welsh and English. Welsh nationalism, or at least Welsh pride, should be a running –if minor-theme throughout the story. The Potters are rich, and in the Wizengamot, but they are not one of the major families of Great Britain, though they are respected. There is a group of Welsh Wizengamot members that meet, and James is quite influential with them, but is just another vote in the crowd of the Wizengamot, while Augusta Longbottom, widow of the Leader of the Light before Dumbledore, wields considerable power on the chamber floor (though not along Welsh Nationalist lines). Also, guess what the national symbol of Wales is, for which the Potters have an affinity.
The Hallows are a source of magical power, and belong to the British Isles, but are most powerful in Wales, where the Peverells met with Death all the years ago. There are other sources and items of other types of power. England has other items of power. Each of the Heptarchy (seven Kingdoms before England) had items of power, though some are lost. The invading Romans had them before the Anglo/Saxon/Danish Heptarchy, as did the marauding Scandinavians; the Deathly Hallows are pre-Roman Bretonnic items of power, centering in Wales. The Veela of the continent have nothing to do with the Hallows, or Wales. Some of the Crown Jewels of the UK are items of significant magical power.
King Arthur, who was a pre-Anglo/Saxon heroic ruler, is a folk hero to the Welsh, who constitute the majority of pre-Anglo/Saxon Brettonics in Great Britain. He also makes up a majority of HP favorite bedtime stories. The Greengrass Family, major nobility in Welsh circles, own the Isle of Man as a personal fiefdom, with near-autonomy from the Ministry of Magic. The Greengrass girls are ignorant of their Gaunt heritage, and the story elucidates their journey as members of the Gaunt protectors of the Resurrection Stone.
Love
No soul-bonds or soul-mates. They don't exist in real life, and they don't exist in the HP universe. These are people that have magic, not magical beings shaped like people. There are those that can still love fiercely, just as there are in the real world, but that kind of devotion takes willingness, compatibility, environment, and time to develop. The first person of the opposite sex that is kind to them will not be their love interest (or only love interest). A childhood crush is just that. Both the crusher and the crushee can grow into a more committed and mature relationship; or one could grow up, while the other doesn't; or they could grow away from each other, pursuing different interests.