Notable Caledonian Figures in Mons Graupius

[Prasutagus]

I am going to write a historical fiction short story from a soldier on the side of the Caledonians a little bit before, during, and after the battle of Mons Graupius. I do not want to write it from the view of Calgacus himself. My many journeys across the internet have not afforded me any historical figure who was on the side of Calgacus. If anyone has any knowledge of someone I could write about, or any tips for the story, feel free to comment.

[Jordanicus]

I fear its all up to you to invent a Caledonian if I were you I would look at the sources about the power structure and social structure. Only source (not trustworthy) is Tacitus's account of the battle.
Hope this helps

[Prasutagus]

Hello! Yes thank you for the reply. I have already written the story (it was an assignment for my creative writing class) and that is exactly what I did. While I would have preferred to not create an entirely new character, it wasn't that bad. Also, I'll keep your suggestion in mind the next time I write something that there is zero history on!

[Nathan Ross]

any historical figure who was on the side of Calgacus.

It's quite possible that Calgacus was invented by Tacitus anyway! His speech is probably fictional, although his name might have been known at the time.

Juvenal writes in one of his satires (set at the time of Domitian) about a British leader called Arviragus, who rides in a chariot. He's probably intended to be Caledonian, but whether real or fiction there's no way of saying.

During the Severan invasion, the imperial party apparently met with a Caledone chieftain called Argentocoxus, who may well have been a real person.

This article, apparently intended for creative writers, reenactors etc, is quite neat and has a good appendix listing known 'British' names. The historicity of some of these is dubious, but most have some foundation!:

The First Thousand years of British Names