Big Sister

There is a subtle similarity to the sisters in their attitudes and talents: Trixie is outgoing, and her talent is that of a stage performer, Checkmate Monarch is an introvert that does not see anypony else as an equal, and her talent is manipulation.
Manipulation and Performance: two sides of the same coin, both can be used to great benefit or to great detriment, Manipulation is not inherently evil for there are different kinds of Manipulation out there, Checkmate Monarch might have just as easily turned her talents to become a Tactician or a Field Commander in Celestias' Finest; perhaps there she could have done the most good and have quickly prevented the Fall of Canterlot at the hands of the Changelings and years later the Storm King.