Dead Man's Party: After spending the summer running himself ragged searching for Buffy, Giles is the first and only one to actually say "welcome home" when she finally returns. He's also the only one who doesn't offer her any anger or blame, simply taking a silent moment to let his joy and relief wash over him while the others make small talk in the other room. He also does a spiffy job of introducing Snyder to Ripper on Buffy's behalf!
Band Candy: Despite Ripper's "indiscretion" with Joyce in Band Candy, there's a great Buffy/Giles moment when he informs her in no uncertain terms that she is *his* Slayer. Their good cop/bad cop interrogation of Ethan in the warehouse is just too fun, and when Ethan tries to sneak up on Buffy, Ripper doesn't hesitate to draw down on him.
Revelations: At a less than stellar moment in their history, the Scooby gang has just found out that Buffy is harbouring Angel. She reacts very defensively and angrily when they confront her about it, and it falls to Giles to remind her of the torture he endured at the vampire's hands.
Helpless: Subjected to the Cruciamentum on her 18th birthday, Buffy is shaken by Giles' betrayal. But when he defies the Council to come to her aid, Giles is fired, his obvious affection for his Slayer deemed "useless to the cause". Both of them stunned, she allows him to tend her wounds while they try to come to terms with what has just happened.
Bad Girls: Despite an enthusiastic greeting from Wesley, Buffy makes it painfully clear that she still considers Giles to be her "real" Watcher, teasing Wesley: "Whenever Giles sends me on a mission, he always says 'please'. And afterwards I get a cookie!" Even though Giles tries not to outwardly encourage her resistance, her loyalty and affection clearly mean a lot to him, and it's only when Giles gives Buffy the okay that she begins to cooperate with Wes.
The Prom
Let the 'shipping commence! For many B/G fans, The Prom was where Buffy and Giles' connection took a turn for the romantic. Having just told Wes to get over his nerves already and ask Cordelia to dance, Giles immediately rises and goes to find Buffy. The two of them smile radiantly at each other, slow music begins to play, and Giles seems on the verge of asking Buffy to dance... when Angel comes in and sweeps Buffy away. Auugh!