Developing a rich storyline for a warrior cat character needs a foundation more solid than river-stones after a thaw. I always begin by placing them firmly within the existing lore—which Clan are they from, and what does that mean for their worldview? A ShadowClan cat might inherently value strength and territory differently than a RiverClan one. Then, I ask questions that complicate their life. Maybe their parent was a rogue, creating whispers of disloyalty they must constantly fight against, or a physical limitation like poor eyesight forces them to rely on a sibling, building a deep, co-dependent bond. The real narrative threads start to spin from how these traits clash with the Clan's expectations.
Conflict is the heartbeat of the forest. A complex plot shouldn't just be a series of battles; it's about the tensions between duty and desire, tradition and innovation. Perhaps your OC discovers a herb that heals greencough, but the medicine cat, bound by ancient ways, rejects it as unnatural. This creates a moral and ideological struggle. I weave in relationships that test them—a forbidden friendship with a cat from a rival Clan, or an apprentice who looks up to them while they're doubting everything they were taught. These dynamics generate internal and external drama organically.
Let the story evolve with the seasons. A great arc shows change. A young, hot-headed warrior might, through loss and hardship, become a strategic and patient deputy, but perhaps that patience curdles into passive resentment. Use the environment as a character: a harsh leaf-bare can force desperate choices, while a Twoleg invasion could shatter their understanding of home. I avoid making them a prophesied 'chosen one'; the most compelling stories are about cats who shape their destiny through ordinary courage and flawed decisions. Their legacy is built one carefully laid stone at a time, not in a single, thunderous battle.