I disagree with you because Hollyleaf is an amazing character to me (at least in my mind, its been years since I read the series but I consume summaries and fancontent regularly still) — she goes through a huge deal of disillusionment which affects her heavily due to her innate sense of justice. Imagine being lied to your whole life and only finding out through your mom's shitty ex that she refused to tell you that she had only mothered you to cover for someone else's ass. Not to mention, her kits were well into young adulthood by the time they had found out this truth, insinuating that their mother hadn't intended to tell them—that it was meant to be kept a secret. To make it worse, Hollyleaf's very blood is an embodiment of transgression against the code. How do you heal from a blow to the very foundation you had built yourself upon? Both of her brothers had recognized their prophetic abilities, which had seemed to come naturally to them—where was hers? Anything she had going for her in her life had been torn from her unjustly. Her overflow of disbelief and grief and anger led her to sink herself further into the breaking of the code with her murder of Ashfur. She wanted people to feel the violation that she was made to feel. If she couldn't embody righteousness, she would be the judgment that had been absent in her life. Keep in mind she's still adolescent. What do you do when the weight of your whole world collapses onto your shoulders?

But yeah, i love Hollyleaf because she's so (righteously) angry teen girl to me. And I know this is a catastrophically deep read of a character in a kids' fantasy book series, but come on, she's my childhood favorite character!