A former Navy Seals member, Sam Fisher was later referred to the Splinter Cell team when he was age 32. He was married to a woman named Jill, and had one daughter named Katie. He later divorced because of 'his dangerous job'.

As a Splinter Cell. Sam Fisher is used to being alone. He is an efficient operative and one of the best.

When Sam was assigned a partner named Toni Soltan, he took the responsibility to heart. Lambert had been right about them, and soon they were two peas in a pod.
When it came to their first mission, however, their friendship would be tested.
Toni was captured by the enemy and Sam was face with a choice. He was haunted by the past of abandoning a former partner a long time ago, so his decision was much different.
He went back for her, and rescued her without compromising the mission. (Although he had to disobey a few direct orders).
Or so he thought.

After several grueling trials it was declared that Sam was a hero, not an insubordinate. Things seemed to be going well.
He and his partner got two weeks of leave.

That was when Sam's and Toni's relationship erupted to a new level. With the freedom and the privacy they soon shared a bed, sleeping in till one pm, after long nights of wild intimacy.
But it was much more then just a simple night in bed together. Sam's feelings grew stronger.

Conflicts with his ex-wife came up, and Katie ended up being kidnapped by their ex-mission culprit's partner. He discovered the identity of Sam, which then forced him to leave the country and revoke his history and citizenship.
With a painful goodbye to Toni, he left for Panama.
He knew that country well.