How different do you think things would have turned out if Rusty had ended up in Shadowclan instead of Thunderclan?
well...i can imagine a few different ways. but!
we know shadowclan takes in loners/rogues (russetfur, boulder). he's a kittypet, which is...different, but still in the same wheelhouse, and a kit. kind of.
brokenstar is also desperate for warriors (he steals kits, remember?) so i think, ironically, he'd be eager to get rusty into the clan and keep him there. there's a solid argument to be made that he wouldn't, but we're not talking about that.
(also, we're not talking about the boring answer where we tweak the starting conditions and put thistlestar in power & etc. boring in that, the differences created are solely cultural, not plot. probably. not sure. the point is, we're not exploring that ATM.)
so i think, and we're going to call him rustpaw bc i like that, i think rustpaw is going to be heavily manipulated from the beginning. like, a kinda "we brought you into this, we can bring you out of it" kind of vibe.
and mm, yeah. rustpaw is still our strongly valued fireheart, but different.
morally speaking, he's torn: he wants to be a good warrior, he believes shadowclan has saved him, etc., but at the same time, he feels like things are wrong.
he can't name it, though, because he has no point of comparison. they don't tell him they're breaking the warrior code.
so rustpaw, and later rust...fang? idk. let's call him rustfang for the moment, but i don't like that, but rustfang becomes an enforcer for brokenstar. a strong backer. his understanding of clan life is, "this is what we do, this is the right way to do it," and that's what he honestly believes.
and brokenstar is very careful about preserving that when he's young, so by the time he's a warrior, it's a very thick shield. even if there's that seed of doubt, well. seeds need dark and pressure to grow, and there's no pressure.
he still gets cinderpaw as an apprentice, mind!, and that's where the story really begins.
there's a scene in "putting roots in my dreamland" where runningcloud (runningnose) tells frostfur's litter that they're two moons old, even though they're three, and we'd repeat that, so that rustfang can still get cinderpaw as an apprentice.
meanwhile! in thunderclan, bluestar never brings firepaw into the clans, meaning tigerclaw's rise to power goes differently.
see, we're going to say that firepaw is a bit of a catalyst, because i think tigerclaw is at his best when he honestly believes he's doing the right thing...he's just warped with ambition.
no firepaw, once he gets the deputyship, he's not in the same rush to kill bluestar.
so, we've got warriors sandstorm, greystripe, and dustpelt. is ravenpaw still around? probably not, he's probably dead. it's not really important. maybe i'll get a little deeper into this and decide it is.
anyway, we're going to make redtail sandstorm's father because it gives us an important thread to pull on: her father is dead. and...the fire happens, maybe that's when bluestar dies. they go to riverclan, and sandstorm overhears someone talking about deputies and who died how, maybe: after all, the leader of thunderclan is dead and the deputy-to-be-leader is tigerclaw, and now she's suspicious.
tigerstar comes back, and sandstorm is wary, but mostly trusting, and clever.
tigerstar makes...i'm not sure? deputy. maybe longtail? maybe whitestorm, because he wants to keep his enemies close. not darkstripe, though: with no catalyst, tigerstar is less of a villain and more of a corrupt politician. i mean, he will be a villain, but he's going to be morally grey for a long time.
anyway, back in shadowclan, rustfang starts to think about how young cinderpaw is. she's adorable! but she's a kid. he was older than her when he was apprenticed, wasn't he? and didn't they say he was apprenticing age?
so yeah. cinderpaw, brightpaw, thornpaw, and brackenpaw are...idk who's apprenticed to who, that's kind of unimportant. but rustfang doesn't know what to do.
blackfoot says they're fine, and brokenstar says they're fine, so they're fine, right?
okay, cinderpaw's first gathering is when she's four to six moons old. brokenstar is smart and doesn't take young bb apprentices to gatherings.
frostfur is there, and she's grieving the loss of her mate and her kits, and brightpaw is really distinctive, those are her kits.
rustfang, who's extremely protective of cinderpaw & co., because she's his apprentice, steps in to defend them, and the litter doesn't know what's going on. (do they remember that they weren't born in shadowclan? yes, but they don't remember who their mother was or any of that.)
they fight. tallstar and...are we at leopardstar yet? not important, anyway, the non-shadow/thunder leaders are like, "control your warriors!" but obviously both tigerstar and brokenstar are supportive of them.
the gathering is cut short, and rustfang. now he's really unsure.
something is wrong.
meanwhile! in thunderclan, tigerstar refuses to confront brokenstar, even if he thinks frostfur might be right. because uh, hand-wavy reason i'll figure out later. maybe he's scared, a prophecy, i don't know. there's a real reason, i just don't know what it is off the top of my head.
sandstorm is pissed. she's close to frostfur! she's angry and unsure and she has to do something.
i don't know where we go from here, but yeah, that's what i think happens.
the next few plot beats involve cinderpaw & co. being rushed to become warriors, so that they can't be reclaimed by thunderclan, rustfang talking to the queens, and sandstorm investigating what's going on.
tigerstar forms tigerclan out of thunderclan and riverclan, nominally to defeat brokenstar, but really, to create power.
i'm not sure what happens to windclan.
blackstar becomes leader, makes rustfang deputy, and we eventually get to a position where rustfang becomes ruststar, and the question is: what kind of leader will he be?
because now tigerstar is fully evil, and sandstorm and some others are trying, but it's not working, we have a pit. greystripe and silverstream have kits when tigerclan is formed, and i'm not sure how that plays out yet.
but ruststar has a decision: help overthrow another leader, or not?