Jacob Leiter

Jack Leiter is a senior intelligence officer within MI6's Delta Section under the Special Operations Department. Jack previously served alongside his colleague and friend, Christopher Leader in MI5 before the latter's resignation.

Jack was one of Chris' closest friends in service and is always on hand to aid him when he calls for it.

Biography
Jack Leiter is the youngest sibling of an American family; he moved to England at the age of 11 to begin his secondary education schooling at Eton College. Following his successful time at Eton, he graduated to the University of Oxford with a degree in European and Middle Eastern languages.

It is also said that prior to joining the Security Service, Jack served in the Armed Forces.

MI5
Jack was said to be among the wisest and sharpest Intelligence Officers in his department and quickly rose upwards in the job; in 2010, when Director General Ian White formed the Delta Elite Team, Jack was among the first, having been hand-picked by William Salmon and was met with high appraisals from both Phillip Turner and the DG.

Jack was often paired with young IO Chris Leader and he mentored him to the best of his abilities, becoming the person he turned to after Ian White.

Moving to MI6 (2012)
Like other agents of his section, Jack was transferred to MI6 following the MI6 Chief's decision to utilise the newly approved assassin's licence scheme. Here, Jack served as a senior intelligence officer alongside veteran MI6 agent Edward (118).

By the time Chris joined the following year, Jack had learnt much about the section he was serving under, including most of its members and MI6 as a whole.

Future At Sea (2012/2013)
Jack showed up in Barcelona when Chris was visiting in July 2012, it was here that he appeared to the latter having acquired a private yacht crewed by members of the Royal Navy. During this meeting, Chris explained his reasons for resigning from MI5 and Jack assured him that their meeting was a coincidence. It is uncertain at this time whether or not Jack was an MI6 although he did state that he had left MI5, leading to the assumption he had transferred around the time Chris resigned.

Jack met with Chris after the pair initated a boat race to Naples, Italy. During this time, Jack and old friend Gareth Destan aided Chris in following up an emergency call made by Andy. When Andy's girlfriend was murdered, Jack rushed to get Chris out of the country and arranged to have Andy and his newborn baby delivered safely to England. It is assumed that Jack immediately investigated the girlfriend's murder shortly afterwards as he had information to hand to Chris when they met in China some time later.

Following the apparent death of Chris' best friend Thomas Grothier, Jack and Gareth accompanied Chris to the funeral.

Jack was instrumental in Chris' recruitment to MI6, as he handed Chris information he knew would be beneficial to his own personal curiosity. It could have been him who asked his brother Robert Leiter to approach Chris in Japan, ready to rendezvous with him personally in China. Jack then gave Chris the information on Andy's late girlfriend and set the stage for his confrontation with the suspected terrorist, Mark Redwood. It was also made clear, at this time, that MI6 were looking to recruit the young former agent.

Jack continued his old role in guiding his young colleague in MI6 and even went out of his way to arrange the delivery of Chris' vehicles to whichever countries he required them, giving him lifts to various places and recommending a bank to deposit diamonds the young IO acquired without asking a single question.