Help! Good new plot needed!

So, to explain what is going on
I started this story a long time ago (i was 11 dammit) and recently i started seeing it from a different perspective, and also realizing how certain parts just did not make sense. So i started reworking on the story, developing the characters better and thinking on how to turn it from a weak fan fiction like story into a real one. Problem is, after reworking it times and times again, the plot became very inconsistent and weak, as it was no match for the newer updates that came. Here's a quick resume:
Two kids leave home after one was stung by a giant scorpion (wtf). They are joined by another kid who, for some reason, is hunted by metal monsters for leaving his job as an alchemist (don't ask, there is absolutely no logic here). On the way, they encounter weird creatures who are either against them completely, or befriend them right away (what). They get kidnapped by pirates, break the ship's curse (oh God), then they meet this weird swamp creature who tells them that the person who could tell them the cure for the scorpion poison had been killed a short while ago. So they are advised to go to the islands that are located in the extreme side of the world to find some kind of oracle that can give them the solution. So obviously, they go there (like any sane person would do). They first need to cross the Land of Dragons (conveniently filled with dragons that will eat anything they see) so one of the kids manages to come up with a trick that turns them all into dragons for a while (u wot m8). While crossing the dragon territory, they meet with a dragon prince who is currently hunted by his uncle's minions. They also learn that the king of the land has also mysteriously vanished, leaving his brother in charge (and this guy tries to kill the prince) (Lion King copy 101). Eventually they save the king and get a free pass until the borders. Once they get out of the Land of Dragons, they change back into their normal forms and somehow save a young witch from a band of wolf creatures, then go to her village and save it from some demon scorpions (srsly?). They befriend the witch, she tags along and they proceed their journey. They meet other creatures, from the desert, who guide them to an alternate dimension (some abandoned old place, idk). From here, they were supposed to get into a fight, then fall into a trap that resulted into a character completely losing their powers. They eventually get to the islands, only to find out that a certain specie that was considered extinct still existed. Then the news spread, the bad guys find out and try to exterminate the creatures once and for all, only they fight back and win (the cure for the poison is eventually provided - the end)

So yes, i know the story is very chunky, stupid and makes no sense, but no matter what i try i cannot find an alternative, so i'm asking for your help. Here's what i need:

1. A good reason for why some children would leave their home - the main plot line, basically (these kids' parents were kidnapped by an unknown force and no one knows what happened to them, therefore these kids are now in an orphanage-like home; also, one of the kids is known to have a supposedly incurable illness - you can use that) - a newer idea implied that someone inspired them leave (like Gandalf did with Bilbo in The Hobbit, idk)
2. Give it an interesting story - (or at least one that is not painfully boring, i'm not pretentious) - add whatever you like
3. This is a fantasy world mixed with some bits of sci-fi, so there might be some interesting weapons, machines 'n stuff (in this world, human experiments are possible and they're commonly used to tamper with one's magic - it can be increased or deviated, you get the point. Keep in mind the experiments were done in the past and they are no longer practiced since the main specie that was used no longer exists)
4. Idk, something cool or unexpected (you can add a twist like, they were initially going for something but then they decide to go for something else)
5. Keep in mind this world is mostly under humanity's control and this affects many native species. There is also one supreme ruler (the guy is actually a puppet controlled by something stronger, you decide what it is)
6. Magic is the main power source here, but it can be taken away/sealed
7. Add things you would like to exist in a fantasy world, anything - make it special
   You don't have to use the original story! It's pretty crowded and lacks a lot of logic, so you can come up with an entirely new scenario! (personally i do recommend replacing it, since it's so bad even i can't see how it works)
   I know i'm asking a lot from you guys, but i just cannot solve this and i need some serious help. I know there are people out there who can really make this great and i promise, that if this story comes out good, i promise one day it will become an animation. (Also, do not hesitate to ask me if you need more info, i'll gladly answer)
   Thank you so much guys, i really appreciate it! Your help really matters to me! Love ya all <3

Your little reactions to things in the first few sentences made me laugh XD

Okay, so you said we can add things—are we allowed to change things at all? Or point things out about the current plot line?

Also, a little info if you can: who are the kids? Genders personalities, motivations? You mention they have powers—what are they specifically? This would really help me :)

@alice i'm glad my little reactions of pain to my past cringe made you happy :'))
If you cannot find anything that matches the current plot line i gave, then sure, you can change things if you need to (i'd really love to keep the part where one loses their powers tho)
About the characters, the first two are a boy (Tanis) - standard confident boyo - and his adoptive younger sister (Narion) - gloomy and tired - who is pretty sicklish, but she can handle it. The other two that join them later are a boy (Alphonse) who acts a little shy and has a passion for drawing ( i have no idea about his powers or even what race he's part of - he does have a crush on the sickly girl) and the other one is a girl (Phoenix), a witch who acts any way but lady-like. Tanis is 13 yrs old, Narion is somewhere around 9 to 11, Alphonse is 14 and Phoenix is 13 yrs old. Tanis is an elf, so you can dig something up from here (he doesn't use much magic in the story tho), Phoenix has standard witch powers (she's mostly using fire and fire related stuff) and Narion, who could have been the most OP character in the group if she wasn't sick, so in theory she has nothing too important. For Alphonse, i already said idk, you can throw in whatever you want (he could have science related powers, for example)
I already created their characters (on my page, do you need a link?)
Tanis - Theyon
Narion - Narion Krysmenor
I recommend you read only Tanis and Narion's pages as the other two are not complete (since Narion and Tanis started the entire thing, you could say the other two just tagged along)
Hope this helps! :3

When I was reading your plotline, my first thought was that it was very "Alice in Wonderland." Then I started drawing connections to "The Odyssey," and "Little Red Riding Hood," and I realized that (probably because you started this when you were eleven) there are a lot of classic fantasy plots mixed up in here. It's like you put all your favorite books in a blender and taped together what came out. (I actually think it's pretty cool.)
So, I have a couple of suggestions for you:
1) Characters:

• From what you've described in Tanis' character chart, he seems like he might be on the autism spectrum, which could definitely add depth to your story seeing as he's a teenager in real life but acts like he's a kid

2) Fixing the Plot:

• I have this wonderful, half-baked idea in my head about what's going on in this world, and it's basically a combination of Inception (that movie about the dreams), Splintered (An Alice in Wonderland retelling that reads like a bad dose of acid), and Land of Stories (Fairytale characters come to life)

3) Solutions to Your Problems:

• What I'm trying to say is that both of your characters seem to have the wonderful childishness and innocence about them that seems at odds with their world, which basically wants to kill them. I'm thinking that maybe the orphanage where they were sent was run by evil witches (think Hansel and Gretel) that feed off of the dreams of children. The witches feeding caused Narion to lose her sight, and they're traveling in order to find a cure for it. Their friends, Pheonix and Alphonse, are also victims of similar abuse.
• The scorpions are the minions of the witches
• The creatures are either for or against them because of a comically complicated political election going on in the forest (one side is for humans/elves, one side is against)
• The pirates are evil soul-snatchers and a benevolent, omniscient spirit is trapped in their figurehead, which the children free. It advises them to travel across the land of the dragons, and to find the portal to the realm of Imagination, (which is guarded by some more nasty witches), where the cure is
• They help the dragons, and in return, they are allowed to pass to the coven of witches guarding the portal
• They save the nice witch from being burned at the stake for not wanting to subsist of the dreams of children and she takes them to the portal
• They sail to the island and discover that the cure the spirit lady was talking about was the horn of a unicorn, which can cure any illness. They don't want to take it however, because unicorns were thought to be extinct and they can't live without their horns
• Tanis accidentally lets it slip that they found some unicorns so an evil guy (think Wiitch King!) wants to kill them for their horn
• They save the unicorns
• In gratitude the unicorns give Narion's sight back happily ever after

Well Ellen, i see you managed to see why the story was so overly complicated :'))) (It's actually a mix between The Hobbit, Quest for Camelot, Avatar the Last Airbender, Lion King, Fullmetal Alchemist, Pirates of the Caribbean, The Wheel of time, Dragons: a Fantasy made real, Dragon Hunters, Samurai X and some other lame details i grabbed from here and there - what was i doing with my life back then?? :'))) )
As for the story line, that sounds really awesome, honestly. You could have ditched most of the things that were in the original story line, as many were simply too extreme for some children or are no longer possible (for instance, Narion is no longer as strong as she was in the original, so performing the dragon transformation would be kinda hard if not impossible for her now)
But you did insert some cool things and i deeply appreciate it.
Thanks a lot!