Caesar was the personal servant droid---a Fill Footman Droid---of the Jod Royal House. Serving the Marchand Family with absolute loyalty since 725 BBY, the droid is as much service & protocol droid as he is assassin, bodyguard & spy. Never having a memory wipe, Caesar's personality and experience skills have only grown, making him an efficient servant & protector. While he primarily accompanies King Alex the "Just" on his travels now-a-days (he was assigned to Queen Heather the "Spirited" before her death and was not with her when she died, as the droid remained at the Royal Palace), he spends the majority of his time at the Royal Palace when the King is not traveling.
Two similar Fill Footman Droids serve the Marchand Family as well, William for Prince Philip & Annabelle for Princess Anastasia. While both other droids have identical software upgrades as Caesar, they have only been serving the Royal Family since 415 BBY & 405 BBY respectfully, giving Caesar far more hands-on experience. Because of this hands-on experience, Caesar is considered the leader & alpha of the 3 droids.