Cristobel Sefton was born to a pair of Betazoids aboard the USS Trillium in 2356. His mother, Damhnait Sefton, was a medical officer serving the crew, and his father, Fortu Sefton, headed the staff of the ship's mess hall. Cris wasn't a fussy child and, outside of school, preferred solitary activities over socializing with the other few children on the ship. In an attempt to provide Cris with large doses of stability, Damhnait managed to transfer between starships as few times as possible.

In his adolescence, as his telepathy developed, Cristobel found it even more difficult to relate to most of the individuals around his age, who displayed almost complete dissonance between what they thought and how they expressed themselves. His new abilities were made even more confusing by the institutionalization of his infant sister who was born with her telepathy fully active. Andraia Sefton has remained a patient in the Cataria Institute for the entirety of her life.

Cris has a somewhat addictive personality; at different times throughout his life, he has devoted himself entirely to single ideas, concepts and constructs. While most of his obsessions have not been long lasting, music and temporal anomalies have been a part of his life for as long as he can remember. His father taught him to play the trysette, a Betazoid instrument akin to a Terran guitar, when Cris was a teenager. Fortu used it to teach his son to harmonize the opposing thoughts and feelings in his head through a technique utilizing musical cadence.

His interest in temporal anomalies began at age thirteen, when the ship Cris lived on had a brief run-in with temporal "hiccups." He never learned the full details of the classified mission, but he immediately began studying all he could about unexplained anomalies in dimensional space and time. He devoted himself to his studies in school for years, to better understand the theories and technologies he enjoyed reading about in his private time. This continued until he was eighteen, when he realized his growing restlessness and frustration with school was stemmed by the purely theoretical study of time and space looming ahead in his academic future at a university or two on Betazed.

Cris immediately applied to Starfleet Academy, where he had a slightly better chance of studying temporal abnormalities up close, and was very likely to discover other, non-temporal, but still fascinating phenomena in a wide range of fields. He began more advanced physical training with his mother, as he continued to excel in his studies, and was admitted to the Academy on his first attempt.

He found his first year in Starfleet Sciences very challenging, as it suddenly seemed like everyone at the Academy was brighter, faster and stronger than he was. As well, his attention became divided by the end of his first year, once he began forming real friendships, now that he was in an environment with more like-minded individuals than he had known in his entire life.

Despite the amount of students who truly understood Cris, there were still many more who didn't quite get him. His refusal to submit to Terran societal norms, such as the use of tact in social situations, made him not terribly popular in the Sol 3-based Academy. By the end of first year, though, he became very close to a trio of other first-year students: T'Pril - a Vulcan, Watson Tuc - a Bajoran, and Solina - a Deltan. The foursome were inseparable for the entirety of second year; a point punctuated by the stylized ring, based on the Betazoid symbol for infinity, they all had tattooed around their right biceps.

Ironically, by the end of third year, T'Pril returned to her distant temperament, Solina had a falling out with the group, and Tuc dropped out of the Academy. Suddenly alone, Cristobel was eager to go on his "cadet cruise" aboard the USS Miranda for his fourth year. On his very first mission, the Miranda encountered a pair of colliding alternative universes, leaving Cris greatly disturbed from meeting a sadistic quantum duplicate of himself. Weeks later, just as Cristobel was beginning to feel back to normal, Starfleet Academy instructed Cadet Sefton to return to Earth. Because of a medical condition in third year, and this more recent upset in Cris' life, the Academy officials were convinced that studying in the academic setting of San Francisco would be to his greatest benefit.

On the last of the several runabout trips it took for Cristobel to be taken to Earth, a mechanical malfunction left his pilot badly wounded, and the EMH offline. Cris attempted to provide first aid to the pilot, but didn't have the knowledge or skill to save her, and the woman died shortly before a starship arrived to assist. By the time Cris arrived at Starfleet Academy, his wavering obsession with temporal anomalies ended for certain, as it struck him that all his knowledge didn't mean much if he couldn't even save a life. Despite the hardship it would cost him, and the intense studies he would have to continue for years after graduation, Cristobel switched tracks into Starfleet Medical.

Corran Quezith, a telepathic scientist whom Cris was close to on the Miranda, came to Earth on Cris' graduation day to declare his love for Cristobel. The pair had courted briefly on the starship, developing a primarily mental and physical relationship. Reunited on Earth, as Cris continued to study medicine, a strong emotional dimension evolved into their relationship. Together, Cris and Corran have joined the crew of the USS Sulu.

Cristobel, like most Betazoids, has an honest, out-going temperament, but, unlike many Betazoids, he lacks an inner serenity of mind. His honesty is absolute, and even brutal at times. Even though he has the awareness to realize what truths certain cultural norms deem to be excessively honest, he refuses to let awkwardness affect how he lives. Because he is always up-front with his emotions, within the limits of Starfleet's social structure, he has little respect for those who perpetually do not say what they feel.

Despite putting the needs of his crew and himself above his desires, Cristobel is typically perceived as somewhat selfish. He organizes his time to maximize the portion of his life he spends enjoying himself. Of all his ancient Earth studies in the Academy, the Terran adage of "Want. Take. Have." spoke to him more than any other. With a fear that his own mind could one day betray him, as his sister's betrayed her, Cris has no intention of letting his life pass him by. He insists on grabbing hold of life, and squeezing tight until it submits to his will, even if feelings get hurt in the process. While he may not constantly consider the direct consequences of his actions, he is always prepared to fully accept such consequences.

Although the Academy has prepared him to fight to defend himself and innocents, Cris is a pacifist, who abhors carrying a phaser. His Betazoid upbringing and the stories he heard of the wounded his mother treated made certain of that.

He's best described as assertive -- always prepared to speak his mind, and follow through with actions. What he is not, though, is aggressive -- he has little interest in convincing others to believe in what he does, since it is so often futile.

Cristobel continues to apply Starfleet Academy's physical fitness regime to keep in peak physical shape for his age and species. He has fairly pale skin pigmentation, the typically dark eyes of a Betazoid, and his hair, which he likes to keep short, is naturally a sandy brown. He has a silver tattoo on his right bicep.