@shinerdrinkerWell, this is hardly a run-away story, just an intriguing though hardly fully thought out story idea. Actually, it's a variation on one I abandoned a long time ago. However, as usual, the idea is how to approach the story.
Since I didn't fully plan it out in advance, but just started writing to see how it might play out, I ran into the same problem as before.
The problem is the initial instigating event. Normally, I'd start with laying out how the character normally lives to set the baseline. Only the story is entirely based on that initial instigating event, making it difficult to lay the baseline, then making it difficult to introduce their normal everyday life after the instigating event.
In one variant, it was more straightforward, the protagonist makes the initial discovery and then tries to deal with a variety of unknowns, not knowing who to trust or which approaches to take—my normal approach to these types of stories.
The other variety is much more preloaded, so there NO CHANCE of detailing their lives until it's already changed each of them profoundly. The idea was to play it as a scientific mystery, yet it's hardly playing out that way.
So, I'm going to have to rethink the story before I can attempt either one. The central issue is that the protagonist is chosen by someone else, who effectively redefines the person and their family and friends (another of my 'group of normal everyday teen friends exploring interstellar space conflicts'). As you can probably imagine, when an outside, alien catalyst makes such sweeping changes, readers would already know why he was chosen, what his plans for them are, all before the normal story begins.
So the whole thing needs to go back on a backburner and stew for a bit, until there's a meaty-enough stew to build full meal out of. Sort of the story of rock soup, before they have the initial rock to share. This going to take a LOT of thought. So the central issue is how to begin the story apart from it's initial instigating event, so it's once again more of mystery to be solved than a forgone conclusion the protagonist doesn't fully comprehend yet.
I still like the two-story approach for this particular story, though the two stories would thus be VERY different, with only the same characters and the same story premise, yet it starts off with a much more powerful start. Therefore, at this point, I'm still way out of my depth. (The whole story is based upon what the various protagonists all share in common and how it affects others around them.)
But once I figure out how to approach it, it should be easier to concoct. And of course, starting big and then using a series of flashbacks to backfill the story might work too.