Arisu Lei

Arisu is the youngest of the Lei sisters - daughter of Anjali Sasyaki-Lei and General Jackson Lei. Born in San Diego while her mother was acting as a section director for Starfleet Intelligence. Something of an accident, born only about 10 years before Julie had her twins, Angel and Olivia, her mother wasn't planning on getting pregnant again. Raised pretty much since birth to be in intelligence and trained in hand to hand combat and martial arts.
Being the 'baby' of the family, Arisu was spoiled a bit more, but spent a lot of time with her big sister Julie. Her goal was to be her sister's partner in the field eventually and then possibly replace her. She loved getting into a good scrape and despite her youth she had a fire and a tenacity that impressed Starfleet Intelligence and the Federation Secret Service.
Quickly rising through the ranks as an operative, she eventually became something of a field leader, even though she was best as an undercover operative. Her beauty and her skill at infiltration got her into numerous terrorist and criminal organizations that she was able to take down from the inside.
Her big sisters Julie and Rumiko eventually teamed up with her and they formed a 3 woman team. Working together closely after the Borg War, she managed to find herself aboard her niece, Angelica Ryder's ship, the USS Mata Hari. There, she was assigned to help with some covert operations, eventually falling for the leader of a covert ops squad, the 141th's MacMillan. She almost accepted a proposal, but for similar reasons to why Angel and her boyfriend in the squad, a man codenamed 'Meat', their long term missions didn't really make a relationship that feasible. 
When Nick Ryder was building up a core team for the Terra Alpha project, she was requested by him personally to help with their Intelligence network. She jumped at the chance. Partially because she had always been attracted to him and after her sister divorced him, she figured she had a shot and they did once sleep together. Although she kind of tricked him into it, making him believe she was Julie although they did enjoy each other's company and didn't entirely mind. It was also during a period of time when he and Julie were on the rocks and didn't quite feel bad about an affair. They still kept it secret and few know about it.
Arisu impressed the 'brass' so much, that when Terra Alpha went independent she was appointed the director of the newly formed Homeland Intelligence agency and given command of a newly constructed intelligence base, the Mount. She loved her work there, until Nick and Noella's daughter Ally St. James, was killed by an escaping convict. Then as time went on, she started to feel increasingly lonely, she wanted to have a family of her own. She attempted to date, but it only caused problems. Eventually she realized that being a Director was not what she was meant to do, she found her skills were atrophying from not being used. And eventually stepped down from the role as Director of Homeland Intelligence, appointing, who she thought was a good fit, Ryouku Sharpe. 
Arisu went to Earth to attempt to take the Imperium and her sister down once and for all. Allying with the Jase'dasis, she found that the 'pull' she was feeling, was the Iljuna and that she had some measure of skill with it, Diving into training and eventually being taken on by Master J'Larin as an apprentice she eventually became a quite adept Jase'dasis pupil and found the peace she was lacking. Content to give up being in Intel, she dove into the Jase with both feet, only to be recruited back into Alliance SHIELD, the rebranded and reorganized Homeland Intelligence she thought she was out of.