Sam and the Presidents:
There are only two real Presidents in the SC continuity: Bowers and Caldwell
President Bowers
At first largely unaware of the Splinter Cell initiative, Bowers used the intel it generated to his political advantage when he declared war on the Republic of Georgia. He then went from acting on Sam’s intel to creating work for him, driving the nation into aggressive action against Indonesian guerillas that ultimately exploded into the events of Pandora Tomorrow.
By the time of the North Korean missile crisis, Bowers was clearly aware of 3rd Echelon and its importance, as he strategized with Col. Irving Lambert on the best response to the problem. While Sam never had direct contact with Bowers, Bowers regarded him as a vital instrument of expressing American foreign policy.
Sam and Bowers’ final interaction was an indirect one, as Sam defused a bomb in Nashville that would have killed Bowers (along with half the city). It was the transition to the Caldwell Presidency that would bring Sam into much more personal contact with the Oval Office.
Conviction
Anna Grimsdottir’s close working relationship with Caldwell translated into high esteem inside the Oval Office for Fisher’s capabilities, and Caldwell tasked Grim with getting him on board to combat the bed of sedition that 3rd Echelon had become under Tom Reed. Before long, Caldwell was taking an active hand in Sam’s field operations – noticeably directing him during his surveillance of Lucius Galliard at the Lincoln Memorial, and personally sending a Secret Service agent to pull Sam out when he was ambushed by Reed’s forces.
The two did not meet face to face, however, until the climactic confrontation in the White House itself. A wounded Sam mounted a heroic effort and took Reed down, saving Caldwell’s life. However, it is what Sam did next that truly impressed the President. Presented with the opportunity to kill Reed in cold blood, Fisher instead stopped himself, forgoing personal vengeance in order to allow the system of justice he fought to defend to operate instead. Impressed by his willpower and his moral fiber (even if she did allow Grimsdottir to gun Reed down immediately thereafter), Caldwell cleared him past the late-arriving reinforcements and let him go his own way. An unspoken understanding existed between the two: each understood the decisions the other made, even if they didn’t approve, and each respected how the other took care of business.
Splinter Cell Blacklist
To Caldwell, Sam represented everything a covert agent should be: honorable, efficient, incorruptible, and brave. She insisted that Grim keep a close eye on Sam while he worked for Victor Coste’s Paladin 9, and when the Blacklist emerged, targeted Sam to lead the new 4th Echelon initiative. This was done over Grim’s objections, but Caldwell knew what she wanted, and how to get it. Offering Sam Fisher the things he couldn’t refuse – operational authority, independence, and the chance to do right by the friend who’d trusted him – made it impossible for Sam to say no. He took the job, well aware that Caldwell had known which buttons to push, and respecting her for her ability to get what she needed to do the job.