Nathan was born in 2212 (64 yrs. old). He ran a caravan route for over 30 years with his wife, Manya. During that time, he became obsessed with the Enclave radio broadcasts. Since then, Nathan has become a fanatic, believing that the Enclave will bring salvation to the wasteland and is trying to convince everyone else in Megaton of this fact. Most of the residents write Nathan off as the local busybody, but all are quick to note that after 30 years on the back of a wagon, he is a considerably good shot.
He will ask you about your opinion of the Enclave. He will praise you if you say they are good; saying that the U.S. is a great country and even though you were born under America (in a Vault), you are still American. If you say something bad about the Enclave, he will dislike you. However, he will like you again if you find him in Raven Rock.
Nathan will be oblivious to the Enclave's arrival in the wasteland (even though it is proclaimed on both radio stations) and cannot be told about it. His dialogue options remain the same.
If he is not dead, he appears in the Enclave's Raven Rock base in one of the cells next to yours, warning "They're not who they say they are, get out while you can, before they get you too!" You cannot make him follow you and attempting to talk to him will simply result in him repeating his warning.
If you do not open the cell where Nathan is, you will still find him alive and well in Megaton after escaping Raven Rock.
If you, or another person kills Nathan, he will often mutter 'Manya' (his wife's name) as he falls to the ground.
On a similar note, if Nathan is killed at Raven Rock during The American Dream, or at all, the player will no longer be able to open dialogue with Manya, instead she will simply acknowledge that he is dead, and will sometimes drift off thinking of him before he died.
There is a typo in the subtitles which can be seen asked "Why do you support the Enclave?"; Nathan's subtitles will read "Because American is the greatest country on Earth", but the grammatically correct "America" is heard in the audio.
He can sometimes be heard humming Yankie Doodle Dandy.
"Now there's a proud patriot. After all, if they could do us wrong, we wouldn't have elected them in the first place, right? Yessir, trust in the judgement of other people to know what's best for me. It's the American way!"
ps3xbox360pc Like all other Megaton characters, Nathan Vargas might go missing or turn up dead. See recovering missing NPC in Fallout 3 on how to resolve this issue. [verified]
pc If Nathan was not freed at Raven Rock, he will be back in Megaton and sometimes he will say the lines he would while captured, such as "Get out of here while you can!". [verified]
ps3 If Nathan was not freed before the destruction of Raven Rock, sometimes he will have the same Enclave-praising dialog options from before he was captured (even though he can be seen re-entering Megaton after his escape). [verification overdue]