Senior Field Agent Timothy McGee, played by Sean Murray, is one of only two original agents who are still a part of "nCIS." Although Tim comes across as a dork, sometimes he can surprise the audience with a dramatic attitude shift.
One such incident happened in Season 4, Episode 9 of "NCIS," when Sarah — Tim's hot-headed sibling — shows up at his doorstep claiming she killed someone. Uncharacteristically, Tim tries to hide
Tim makes seemingly every wrong move in this episode to protect Sarah and even quits his job in anger, although Gibbs eventually gets him back. It was a genuinely shocking moment for the viewers, who are used to Tim's level-headedness and haven't seen much of this side of his personality.