Background
Mithros, like most, was inducted into the Jedi Order at a very young age, the only thing linking him to his past being a small heirloom: a silver cloak clasp in the shape of an open rose. His youngling training went by without much incident, proving to be an amiable and high-spirited individual, picking up lightsaber combat very quickly and picking up the basics of using the force, though mostly using them to mess around and cause mischief in his youth.
Despite this, there was always a feeling of mistrust and reluctant tolerance of his presence from the council, and not because of his carefree attitude. They saw something in him that made them uneasy, and this stayed at the back of his mind throughout his training. This was reflected in his master, who was cold and distant. Throughout his time as a padawan, there were moments where his master would look at him, and he was sure he saw fear behind his eyes.
Upon attaining the rank of knight, he confronted the council regarding this suspicion. They revealed to him that his ancestor was a master of the Jedi Order, Nilana Shylan: The White Rose of Typhon. They told him the tale as they knew it, how she fought against the Sith before the first Galactic War thousands of years ago, but when the time came, and the Sith declared open war and unleashed its legions upon the galaxy, she vanished, deserting the order for someone she loved. When Mithros first arrived, they sensed something within him, and when they searched through the force for the route cause of this presence, they saw Nilana, her back turned to the order alongside a figure shrouded in shadow. Their unease was based on what Mithros represented, the product of a Jedi who let personal attachments get in the way and shy from her duty, and while he was many generations down the line, the sins of his ancestors' past haunt his every step, with a sinister shadow in his wake.
Before he could investigate this further, the Clone Wars broke out, and he found himself sent head first into battle against the CIS. Mithros has taken this change of pace rather well, relishing the challenge and the thrill of battle. While he still adheres to the code, that does not stop him from using his tricks in the force and skill with a blade to taunt his foes and ultimately enjoy himself.
Motivation
Uncover the past - Mithros wants to know more about his ancestor Nilana, and the truth behind her desertion from the Order.
For the Republic - Mithros is no stranger to oppression, and is thus a firm believer in what the republic stands for: freedom. He will stand as an immovable object against the tyrant, the oligarch and the oppressor, and will not back down when the people they have sworn to protect are in peril.
Brothers in Arms - Despite the attitude of the Council, Mithros enjoys the company of his brothers and sisters of the Order. Seeing them as family, he is always happy to see them and is usually ready and eager to help them if they ask.