"Brahne Raza Alexandros XVI is Alexandria's ruler and mother of Princess Garnet in Final Fantasy IX. Though she ends up causing much death and destruction, Garnet testifies she had once been a kind and well-liked monarch and not the power-hungry villain she became after her husband passed away and the mysterious Kuja started to show his face within Alexandria Castle."  -Wiki

Her voice is completely up to your own interpretations, but keep in mind she can go from motherly to crazy and her certain character traits when auditioning a voice.

• She's insane, conniving, spoiled, corrupted, but before she was kind, caving and nuturing.