This is a bit of a "companion" OC; Riverpaw is the sister of Pearlshell.
Riverkit was born to Reedpelt and Shimmershell, along with Pearlkit, Stripekit, and Sweetkit. While the "tougher" kits of the litter, namely him, Sweetkit, and Stripekit, learn to fight, little Pearlkit stayed behind like a silly coward. He takes on the role of bully to her, taunting her about her shyness.
A bitter strife grows between the two siblings, escalating with each passing day. Just when it seems like the quarrel will never end, Riverkit sneaks out of camp to explore. Pearlkit follows him, stalking him like prey, hoping to scare him. Just as Pearlkit is about to pounce, a hawk swoops down from the sky and snatches Riverkit. In a burst of energy and bravery, Pearlkit leaps onto the hawk's back from behind, ripping its throat and killing it. But, it is too late for Riverkit. Chest pierced by the hawk's talons, his uses his last breath to apologize and beg for forgiveness. Pearlkit forgives him and apologizes too as he dies under her paws. As Riverkit is born into StarClan, he witnesses his siblings' -now Pearlpaw, Stripepaw, and Sweetpaw- apprentice ceremony. In a last act of respect to him, Mistystar names Riverkit as an apprentice- Riverpaw. Riverpaw enters StarClan happy- happy that he was now Riverpaw.