G-Man's and Breen's speeches at the beginning and at the end of Half Life 2 and G-Man's anger at the start of Episode 1.
Rise and shine, Mister Freeman, rise and... shine. Not that I wish... to imply that you have been sleeping on... the job. No one is more deserving of a rest, and all the effort in the world would have gone to waste until... well... let's just say your hour has come again. The right man in the wrong place can make all the difference in the world. So wake up, Mister Freeman...wake up and... smell the ashes.
Tell me, Dr. Freeman, if you can. You have destroyed so much. What is it, exactly, that you have created? Can you name even one thing? I thought not.
The last quote really makes me think.