Angelica Elizabeth "Angie" Maitland[1] was the daughter of George Maitland and sister of Artie Maitland.
History
After her mother passed away, Clara Oswald became her nanny. (TV: The Bells of Saint John)
Angie discovered photographs of Clara Oswald on the Firebird in 1983, at Caliburn House in 1974, and a photograph of Clara Oswin Oswald in Victorian London. She and her brother used these photos to confront Clara after she got home from Victorian Yorkshire and deduced that Clara was a time traveller. Angie threatened to tell her father about Clara's secret unless Clara agreed to take them on a trip with her. (TV: The Crimson Horror)
The Eleventh Doctor took Clara, Artie and Angie to Hedgewick's World of Wonders. After riding the Spacey Zoomer Ride, Angie got bored and wondered off to the punishment platoon barracks. There, a Cyberman arrived and kidnapped her; her and Artie's child minds were used to build the Cyber-Planner. Put into a walking coma and not fully upgraded, she was finally released when Mr Clever freed her and her brother once the Doctor sacrificed a chess piece in their game for control of the Doctor's mind. Clever threatened to have Webley kill them, but Emperor Ludens Nimrod Kendrick Cord Longstaff XLI used a hand pulse to deactivate him. The Doctor picked up the pulse to distribute Mr Clever among the army of Cybermen.
The Emperor set off the explosive to implode the planet with the Cybermen still on it, which drew the attention of his ship. The ship transmatted the Doctor, the humans on Hedgewick's World and the TARDIS on board. The Doctor then returned Clara, Artie and Angie home. (TV: Nightmare in Silver)
Back in London, Clara prepared to make another of her mum's soufflés for Angie and Artie, to Angie's displeasure. Angie told Clara she had a letter sent to her. The letter held a soporific which caused Clara to fall asleep. Later, when George left the house, the Doctor agreed to take care of Angie and Artie, demanding that they couldn't go to the cinema until Clara woke back up. They tricked the Doctor into playing blind man's buff, which Clara realised after waking up was a ruse to get to the cinema. (TV: The Name of the Doctor)
Personality
She felt very strongly and often said that Clara was not her mother. She acted like most teens towards adult chaperones. She and her brother also thought the Doctor was Clara's boyfriend. (TV: Nightmare in Silver)