Kar

Kar was a Pictish teenager. When the Ninth Legion invaded her homeland, she released a monster to unleash war upon them, but the beast continued its rampage and caused the deaths of her elders. Believing the decimation of her community was her fault, Kar became a leader and protected those who remained.

Unleashing the Eater Of Light
Kar lived in the Aberdeen area of Scotland in the 2nd century with her parents and brother. When the Ninth Legion of the Roman army invaded her homeland, Kar was given the role of Keeper of the Gate while the older members of her community went to fight. She guarded a portal between dimensions with the Devil's Cairn. Believing that the Eaters of Light which resided on the other side of the portal were the only things strong enough to defeat the Romans, she allowed one through. The beast destroyed the Roman legion and continued to unleash terror upon her community.

Protecting the survivors
In an area of woodland close to her home, Kar was witnessed mourning the loss of her community and the deaths of her parents. Upon catching sight of Bill Potts, she picked up two swords and chased her until Bill fell into a pit trap.

Kar returned to her community, carrying her "crazy novelty monster killing tool", where she encountered the Twelfth Doctor and Nardole. She explained that she was the Gatekeeper and lied that she had killed the Ninth Legion in a great battle and called the Romans cowards. The Doctor and Nardole escaped in an explosion of popcorn.

Kar and a group of Picts caught up with Nardole. She watched as the Doctor entered the cairn, stating that he wouldn't return.

Making amends
Two days later, she was surprised when the Doctor did return. She told him about the Eater of Light, and how the she had released it to unleash war upon the invading Romans. Encountering a dead Pict in the woods, Kar believed the death was her fault and felt it was her duty to stop the beast.

Kar opposed the Doctor's idea of sacrificing himself, and believed it was her time to fight her fight. She went into the portal and fought the Eaters of Light alongside Lucius and the remnants of the Ninth Legion.

Legacy
Ban carved her story into a Pictish stone and taught the crows her name: Kar. (TV: The Eaters of Light)