Lightning
Cloudtail in A Dangerous Path:
“Lostface!” Cloudtail spat suddenly. The venom in his voice startled Fireheart. “I hate that name,” he hissed. “What right does Bluestar have to remind her of what happened every time a cat speaks to her? Well, I'm not going to use it again. And if Bluestar objects, she can…she can go and eat snails!”“Go and eat snails” is just so random and doesn't sound as fierce as the rest of his dialogue there.
I forgot that line even existed oh my god.
And this gem from Fire and Ice proves Graystripe is just a giant kitten:
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Cinderpaw raced down the slope, across the hollow, and up to Fireheart's side, sending fallen leaves flying everywhere.
Graystripe leaped up and caught one as it drifted past his nose. He pinned it to the ground with a purr of satisfaction and saw Brackenpaw staring at him. “Er, never miss a chance to practice your hunting skills.” Graystripe told him quickly.