i feel like rn the best thing to do would not be open up the past ic, but start it from current events and take it from there. again, there's not much to work with as everyone's so damn neutral and isolated, but like.....sun's gonna bring ash here to heal from riverclan, maybe something could happen between them? Lamb's currently having awful falsities about darkclan and you said you were gonna have her come to darkclan? maybe they could also start something, whether it be a really close friendship as the two clans realize they can trust on one another, or lamb can keep her ideas and start to hate and resent darkclan and have stuff like that. really i feel like those might be our best things to start, hopefully we can start a trend of clans interacting with one another and we start getting plots with our neighbors of shadowclan and windclan (and the tribe!). but start with riverclan and thunderclan. especially as sun has a decent shot at being the new mca of riverclan and as a darkclanner and dusk's son that could be interesting and im totally willing to work with his relationship as a riverclanner/darkclanner to boost both clans!
god, i just want sun to be a bit older now and half his plot already done with, because he's meant to/was created to spark drama between clans but he's just a little baby still and isn't in the time of him life and path that he can do that.
and hey ren, it's okay! i mean, characters always have depth to them - it's just a matter of how far down you, as the writer, is willing to go. people can seem 1-d or 2-d but every single person alive is multidimensional and have so much history and neaunces that isn't clear to most people. like getting to know a stranger, you have to get to know your own characters. what makes them tick, why they're like they are, what they came from and how that affects them. explore her! im certain if you spend some time getting to know her, maybe fleshing out her backstory, writing oneshots trying to get inside her mind, using an event or two to also try to get inside her mind and how it affects her, then you'd find she has flaws and strengths and depth as well.
and then once we find those flaws we exploit the hell out of them lol