The sun and radiation filled dust of the Capitol Wasteland can get to the toughest beings alive, including the Mysterious Stranger. But he could'nt let that stop him. He had to find shelter and quick, for his dog was about to have puppies. The Mysterious Stranger eventually found the perfect spot. It was a cave that led to Vault 101's hugh metal door. He wasn't worried about anyone walking up on him (Vault 101 has never opened its doors). So he layed out some pre war newspapers just outside the metal door. He could tell the puppies were comming, so he walked away for the dog's privacy.
The Mysterious Stranger waited at the mouth of the tunnel. That is, until he heard a very odd sound- it was almost like a car without weels being dragged across the road. He suddenly realized it was comming from inside the tunnel- the vault door was opening! So, out of pure instinct, he ran back to his dog to see a baby pup licking its dead mother. The sight was sad enough for the Mysterious Stranger to tear up. But what caused him to tear up was the fact that his tough-as-nails dog to die giving berth.
Unfortunately he didn't have time to grieve. He had to get the pup out of there ,and he had to do it fast. He scooped the whinning puppy up with one hand (despite its protest) and ran out of the tunnel as fast as he could. He got out just as someone walked out. The Mysterious Stranger struggled to the top of the cave's hill, and watched as a man in his mid forties and dressed in a lab coat walked out into the open. The man set down an outdated voice recorder, then walked out into The Capitol Wasteland.
The Mysterious Stranger walked down and picked up the voice recorder. He played the recording which said, "Son, if you found this, it is too late to go back into the Vault. Do not try to find me, it will be too dangerious. I Iove you, son. Go and stay at a town called Megaton. Goodbye, son." The Mysterious Stranger walked out into the Wasteland, replaying the recording and holding his new dog. Little did he know that a young waunderer had also came out of the vault, looking for his dad. And the dog? The Mysterious Stranger named him Dogmeat.