Katriona

Three, seven, ace!

Katriona is played by Maybell Marten. She is a minor character in Mabel.

Season Seven
Kat's only canonical appearance is in Episode Forty-Seven: What Happened in the '20s. She breaks into the Martin House with her friend Res and explores the place, finding a strange painting that her and Res study. After she yells "the door is going to open!", she and Res are presumably pulled into the Underhill.

Trivia

 * Kat's name means "pure."
 * She appears to enjoy The Queen of Spades by Alexander Pushkin-- one of her reoccurring lines is "three, seven, ace!"
 * She tends to be imaginative and loud; Res seems fondly resigned to chasing her around.
 * When Res asks her to swear she's telling the truth, she swears on "teddy". The curator chooses to believe she's swearing on a stuffed animal.