This WMG page contains fan theories for both the Fan-Fic and the movie of the same name
Guesses for the Fan-Fic
Serious Wild Mass Guessing
The Chibi-Usa of this continuity is the demonic daughter of Ranma and Succubus-Usagi.Pluto claims that Chibi-Usa is the result of artificial insemination using some of Mamorou's stored sperm, but she's clearly bullshitting her way through that, not to mention Usagi is clearly squicked out by the prospect. The author has teased us with a possible Usagi/Ranma pairing, and made a point of mentioning that there are two methods of creating daughter succubae, one of which involves a rite of some sort (and possibly involving impregnation with a Succubus' tail), but has only shown the quasi-vampiric method so far. Also Chibi-Usa seems to know a lot more than she lets on (including knowing about Ranma), and is a lot snarkier than previously in canon. Conclusion: She is a birthed Succubus who hasn't reached sexual maturity yet.
Mamorou isn't really deadHe's Just Hiding.
Pluto will end up becoming a SuccubusMainly because she is really appalled by the prospect of Usagi becoming one and rather dislikes them, I doubt the author can resist the temptation to turn her into one (that is if she isn't already one and just figured a way to hide it).
Queen Serenity really has been reincarnatedAnd is Eve. Both were/are willing to do what has to be done and have been painted as being incredibly ruthless. Also it'll give Eve plenty of angst about being so ready to off Usagi. Alternately Serenity has been reincarnated as Genma, just for the sheer Mind Screw value.
Genma, at some point will make a Heroic SacrificeHe's been on the path to redemption for a while now, and this will result in Redemption Equals Death and give Ranma the final push to become the Princess of Earth.
When a male is turned into a Succubus she takes the form of his ideal woman.This may be canon and I just forgot, but Nariko is an elegant, but kind hearted, woman. Eve is the very model of the Germanic (or stereotypical version at least) ideal of beauty and power, Morgan is short and cute, and Morrison is pretty much a generic female agent (which fits with his crush on Andrea). Misako/Aurora is a special case due to Alexia's alterations. Eldritch Abominations exploding into theirs. Kinda describes the Eva-verse really.note
Queen Serenity in this continuity was reincarnated as Otto von Bismarck and then David XanatosHer plan is still running, even several millennia after she died, hell even worked out how to make demons reincarnate, which apparently is simply not possible. She was probably Queen Elizabeth and Machiavelli too.
The Church of the Assembly of Man eventually get their act together.And the next time we see them is in Doctor Who where they are fighting the Weeping Angels.
Guesses for the Movie
The Box contained Stolen MoneyFather was part of a gang of criminals. The gang stole some money, hid it, and then parted ways, waiting for things to cool down before spending any of it. One of the other criminals was put in charge of finding a place to hide it; he chose the island. He then gave the map to Mother sometime after she and Father had split up, for safe-keeping. Ten years passed, and this criminal died sometime in the interval, but not before telling his colleagues about the map. Father then showed up at Mother's house to get said map. He lied and told her that if she tried to call the police or intervene in any way, his colleagues (who he claimed were close-by) would kill her and the boys. Feeling confident that he had successfullly intimidated her, he then went to sleep right in her house. Mother kept the map all these years because she knew that he or someone from the gang would come looking for it, and she was afraid of what would happen if she no longer had it. Father invited the boys on the trip to (unbeknownst to them) act as hostages to make sure that Mother didn't call the police after he'd left (and to make sure that she hadn't given him a fake map). This is why Mother looked so scared throughout the movie. Father, however, has a Hair-Trigger Temper, and nearly sends the boys home despite the fact that he needs them as hostages; whether from cooling down and coming to his senses or from orders received from his colleagues over the phone, he changes his mind and stops the boys from going back home. At the very end, he seriously was contemplating killing Andrei and Ivan because he no longer needed them (as he now had the box). When he held up the axe to Andrei, he really was about to attack him with it. When he chased Ivan up the tower, he was only pretending to suddenly care about him in order to coax him down. Luckily for Ivan, Father slipped and fell to his death; however, since they never knew for sure that he was evil, his death feels like a tragic loss to them, rather than a triumphant victory. Father and Mother had two pictures taken, one with Father and one without him. Ivan and Andrei only ever knew about the one with Father. Thus, when they see the picture in the car, they mistakenly believe that Father was supernaturally removed from the picture. Now as for what the symbolism and religious references mean in relation to all this, Father is simply a counterfeit Messiah, a symbol of false, dashed hope; considering the movie is a study on troubled father-son relationships, this fits rather well. Father shares some similarities to the Biblical account of Jesus (the way he appears in his very first scene, his having eaten a lot of fish once), but it quickly becomes clear (to Ivan, but not to Andrei) that, where it matters, he is the exact opposite (the most blatant example being how he becomes angry with the boys for forgiving somebody; clearly a striking contrast for anyone who is familiar with the New Testament). The movie seems to basically be saying that we should be careful who we admire; there are those who are not to be trusted or followed, and Father is, by all appearances, one of those people.