Fable 2: The Perfect World sequence is High Octane Nightmare Fuel for a reason, but if you pass it? You hear Rose's voice telling Sparrow s\he had passed the test and obtained the one object that can defeat Lucian, encouraging her sibling to confront him.
After the Prince/Princess is crowned in III. There's something about Logan's shocked, completely genuine smile in the middle of all the crowd's booing if you choose to spare his life.
If you have a daughter (adopted or not), you can pick them up and hug them. There's a likely chance that when you do, she will say "Snuggles!" in the most adorable way possible, you can't help but grin at the sheer amount of heartwarming to be found in that one word.
In Fable II when you return from The Spire after ten long years of abuse and your dog is the first one to greet you off the dock, complete with face licking and just being so damn pleased to see you again.