on Reepicheep and his character arc.

Reepicheep wants to be valiant. More than that, he wants to be seen as valiant. It ties to his personal honor. Never more clear than at this scene:

Aslan: I have sometimes wondered, friend, whether you do not think too much about your honor.  Reepicheep: Highest of all High Kings, permit me to remind you that a very small size has been bestowed on us Mice, and if we did not guard our dignity, some (who weigh worth by inches) would allow themselves very unsuitable pleasantries at our expense.

And to be fair it’s quite true that the mice are constantly underestimated. But it is not this which convinces Aslan to restore Reepicheep’s tail, it is both because of their ancestor’s actions (chewing the cords which bound Aslan to the stone table) and Reepicheep’s followers’ willingness to go without their own tails, not taking an honor denied to their chief.

I think his desire to be valiant (more than wanting to be noticed as being valiant) actually comes from a desire to be like Aslan. Earlier in his arc I think this virtue was twisted into pride, but at the least I think that begins to be transformed by his encounter with Aslan at the end of Prince Caspian. As his arc progresses, he gradually lets go of the need for others to see it (culminating in his throwing his sword away, as well as allowing Lucy to cuddle him when they say farewell, something he would never have allowed in Prince Caspian). Last time I reread The Voyage of the Dawn Treader, I nearly cried at the contrast in how he treated the giants in Prince Caspian to how he comforted Eustace under the dragon enchantment. Eustace, who as a cowardly boy had insulted him worse than the giants ever did. Just… Reepicheep and his character arc.