Cecil sighs a bit himself, at that. "No, nothing ever does. Even the things you think are undying and ceaseless are, when you get down to it, ephemeral and fleeting. It can really get you down, some days." External circumstances have a way of ruining everything, just when you think your life is well and truly sorted out.

"What exactly did you protect the Earth from?" The obvious answer is extra-terrestrial beings, like it's right there in the word extra-terrestrial, but you never know. Maybe one time Ianto flew around the Earth counter to its rotational direction to set back the clocks, or punched a meteor. There's a lot of possibilities.