I'm That Guy
I'd be the guy that uses a time machine to visit the past, and immediately meet a wonderful girl who then perishes in the catastrophe I wasn't allowed to prevent.
Later, on a beach and down to my last pair of jeans, with a beard and my naked feet calloused from shells, I'd find a bottle with a message - a heartbreaking message from the wonderful girl! "My love, meet me at -" and then a water stain smeared the latitude and longitude, rendering them indecipherable.
Months go by. On my balcony in Del Fuego a lizard is sunning itself. On impulse I try to catch it, but it darts into a crevice. I poke into the crevise with a stick, and withdrawing out the stick I find a key on the end of it. The key fits a door in the basement - a door no one has opened in years - it is clotted with dust and webs. I turn the key in the lock, and swing the door open to find myself in a familiar room, and in it is the time machine. I step into the room - the door behind me closes up into solid wall. There is another door in the room, which is one of the ways out. The other way out is to use the time machine, the controls forever set to the past, to the catastrophe. Somewhere there is a ticking sound, and a fly meanders through the air.