Haku from Naruto for the bingo!
Haku always felt like the foundational marker to Itachi to me. The Wave arc was the truest bit of writing in Naruto tbh, Kishi was actually writing a story there as opposed to blockbuster manga stuff. And Haku was everything that was good and bad on the kekkei genkai lore. He was a mirror to Sasuke, who people feared bc of the sharingan. He was a mirror to Naruto, because he didn't ask for any infamous abilities. And his relationship with Zabuza is a direct mirror to Naruto and Kakashi because both Haku/Zabuza abandon their villages because of what the village has done to them as opposed to Kakashi and Naruto who still stan the leaf village for God knows what reasons.
Haku was probably what Itachi might have become if he and Shisui left the village instead of doing whatever the heck Kishi wrote. A gentle little dude who could murder you without breaking a sweat but didn't because he was first and foremost, human. God I miss early naruto 😫