Esteban was orphaned at a very young age and was primarily raised by his grandparents as if he were their son. This would teach Esteban the value of family, and though he would grow to become quite selfish, his relatives would remain deathly important to him.
At some point during his teenage years, however, Esteban began to crave power. To obtain it, he made a deal with a ruthless sorceress named Shuriki. The two made a deal that included Esteban helping the sorceress to take control of Avalor, on the condition that he will be granted a healthy amount of political control under her reign. Esteban also had Shuriki promise to keep his family safe during the purge, but this particular agreement fell on deaf ears as Shuriki's first action was the assassination of Esteban's aunt and uncle, Queen Lucia and King Raul. Esteban's grandparents and Isabel were placed in an enchanted painting by the Royal Sorcerer Alakazar, while Elena was apparently killed by Shuriki as well. As the only surviving member of his family, Esteban was riddled with guilt but was nevertheless hailed as the new Chancellor of Avalor under Shuriki's order, as promised.
With her selfishness and vanity keeping Shuriki from actually caring for the kingdom's welfare, Esteban put his intelligence to good use by ensuring that the kingdom remained financially prosperous and outwardly appealing over the following decades in spite of their tyrannical ruler. While he disliked Shuriki's rule later on, he refused to oppose her, believing that there was no chance of success against her. Once Elena reclaimed the throne, Esteban would maintain his role as chancellor, though he refused to confess to his treacherous actions, instead claiming that his partnership with Shuriki was completely unwilling.
As Chancellor of Avalor, Esteban is very knowledgeable of the Kingdom of Avalor and, as he himself boasts, knows "anyone who's anyone in Avalor". He is also a firm adherent to etiquette. He is shown to also be both shameless and a bigot; because of this, he can be snooty and is not liked much.
He believes Elena is too young to bear the responsibilities that come with ruling a kingdom and disapproves of her personal approach to leadership to the point where he constantly seeks to undermine her and become viewed amongst the citizens as "the true power behind the throne". He dislikes being reminded that she is the one in charge, which ties into his overall intolerance of being told what to do by others.
Unlike Elena, he is happy to delegate responsibilities to others and simply give orders from the sidelines. Despite his differences with Elena, however, he does care about her enough to want to keep her safe and values his family quite enough. In fact, in "Island of Youth", he chooses to save Elena's life rather than retrieve his canteen to keep himself young.