A: It's you, apparently. You're a time-traveling adventurer, armed with a trusty pocket watch and a penchant for getting lost in the timeline.
A: To prevent paradoxes, of course. Or, if that's not possible, to make a really cool-looking clock tower in the middle of nowhere.
A: You have to be chosen. Or, you know, take a few minutes to practice your ninja skills and a few more to learn basic first aid. Then, just go with it.
A: Don't touch any of the shiny objects. Don't eat anything that looks or tastes like chicken. And, for the love of all that is temporal, do not attempt to recreate the plot of 'Back to the Future'.
Advanced Time Traveler's Guide