Need help with creating OC Clans

Hey! I'd like to think of myself as a bit of a fanclan wizard, and I'd love to help!

When I start making a Clan, I like to start with a few details, then ask a few questions, and flesh that out with more details! You have a great starting point with this rogue Clan, so perhaps that can be central to your build. Asking questions like: how did the other cats feel about this new Clan when it was formed? Did it create tensions? wars? Was any of the Clans friendly to them and try to help them? Why did they make a Clan in the first place?

I love making very grounded and nuanced builds, so I like to go with the "external + internal pressure = result" approach when creating worlds. That is, that every fun thing you'd like to add (a Clan of former rogues, for example) needs to have some external pressures that caused cats to make that choice, as well as characters that had a reason to stick to that result. By doing my builds with this method, it ensures that there's always a logically sound (and typically very exciting!) reason that my fanclans deviate from the "norm", which helps keep everything internally consistent and prevents stinky plot holes. (You really don't want to get dozens or hundreds of hours into a build to find that your foundational principals are built on shaky premises that don't hold the weight of later ideas!)

There's no one that can really help you with making ideas, that's up to you! Drawing inspiration from a wide array of media and sources can help, as well as placing the Clans in an interesting location: a setting can do a lot of heavy lifting with culture and conflict, if you simply ask "what are the struggles of living here?" and answer "how do each of my Clans go about solving these struggles?"

making a few core characters and asking "what does this cat want?" and "how far are they going to go to get it?" are also helpful cores that can build a strong world! Don't get too attached to these firestarter characters, though, as to really kick a build into making change, they have to have very strong desires and go to great lengths to achieve them--some of these will end up as your "villains" depending on the way your modern timeline shakes out!