John Sentinel was born to an unknown Chiss female in POW camp aurek based on the north eastern part of Alderaan. His father was an Imperial spy for what is now known as the Sith Empire, at the time the faction was mostly unknown to Republic Intelligence. After being born the child now known as John was separated from his mother and given to a foster family the Sentinels a Human family that served House Organa. At the age of 17 John "Sentinel" was recruited at the local recruiting office near house organa after hearing about the sacking of Coruscant. He was sent to training. He excelled in basic training, but had difficulty talking back to officers, which would hold him back in the progresson of his carrer. After basic training he was stationed on the Gav Dragoon and served in extraction of friendly forces behind enemy lines. In 3649 he sustained major injuries to the lower back and legs. Cybernetics replaces several bones and some muscles in order to continue on in his carrer, thus his endurance, when on foot, is greater than that of non augmented soldiers. In 3647 he was inducted into the Republic Navy and served as a special operator for critical staging areas on major planets securing landing zones with his unit the "Pathfinders". Later in the year 3643 he was invited to join UAF JSOC where he now serves as a staff sergeant overseeing School of Infantry and training.
His parentage with Imperial mother and father may affect him and his duties, although he was raised with republic values he has always shown an interest in his biological parents this may cause problems he must not learn about them. He has shown his loyalty to the republic throught various operations with the republic. His conscience may hinder him from doing what must be done in certain situations. He has a history of stim addiction after his injuries he was addicted to pain killers to dull the pain of the newly installed cybernetics.