Olivier Mira Armstrong

Major General Olivier Mira Armstrong is Alex Louis Armstrong's older sister. She is in charge of Briggs, the northern military border. She scoffs at the concept of "equivalent exchange" and believes "survival of the fittest" is the only law in life. Her subordinates are loyal, but if it ensured the survival of Briggs (or for the sake of the greater good), they are instructed to leave her to die if ever the need arose, and she wouldn't hold it against them. She can't stand Colonel Roy Mustang, and she is brutal towards her little brother. She considers both of them to be weak and insults to the military.

One of her closest subordinates is Major Miles, a soldier whose grandfather was Ishvalan; he is of many bloods due to several inter-racial unions, beginning with his grandparents. It is possible that he is also part Xingese, but his Ishvalan blood is the most prominent.

Olivier assists Edward and Alphonse after the homunculus Sloth infiltrates Briggs by accident. She helps them out because of personal reasons and her determination to protect Briggs, even if it is from the military itself. She thinks of Edward and Alphonse as whiny children, often calling Edward "Red Midget."

After having killed the corrupted general Raven who ordered her to set Sloth free, she answered Führer King Bradley's summon and went to central where she was given Raven's seat at Central military headquarters. The other generals showed them their army of lesser Homunculi and told her their plans, but in fact she was held hostage to prevent her soldiers of Briggs from rebellion, which they did nevertheless.

When Roy Mustang started his attack, she mocked the corrupted generals, stating that as they always stayed "comfortably" in Central, they never knew what was a real war and were unable to deal with it directly. She then killed one of the two generals and took the other hostage but Sloth, sent to deal with her killed him by surprise. Thanking the Homunculus for preventing her from having to "dirty her blade with that scumbag's filthy blood" she fearlessly engaged a fight against Sloth and the lesser Homunculi, soon joined by her brother and then by the soldiers sent to kill her whom she convinced to "Act on their own for once". After a long and hard fight, they are saved by Izumi Curtis and her husband.

Powers and Abilities
Being the General of Briggs, Olivia has full command of the Fortress. She is also very skilled with her family heirloom sword

Trivia

 * Like nearly all military personnel in the Fullmetal Alchemist series, the Armstrong family is named after a military vehicle, vessel or weapon, in this case, the Armstrong Whitworth Whitley (A.W.38 Whitley), a British bomber from early WWII