Following in His Footsteps

Following in His Footsteps is a main quest in Fallout 3 as well as an achievement/trophy.

Synopsis
After following James' trail out of Vault 101, the Lone Wanderer continues the search in the nearby Megaton, following their father deeper in the ruins of Washington, D.C..

Walkthrough

 * This is a lengthy quest that will take the player across a good part of the wasteland. Questioning Megaton citizens about James will point to Colin Moriarty, owner of Moriarty's Saloon. The local entrepreneur will instantly identify an opportunity to profit from the information they have. To obtain the information, players can:
 * Pay 100 caps (the price climbs to 300 if the player refuses to pay, then changes their mind),
 * Complete 300 Pieces of Silver, dealing with a former employee of Moriarty's hiding outside the town, in Springvale.
 * Pass a Speech check.
 * Steal the information from Moriarty's terminal in the backroom of his saloon. The password can be obtained from Nova, after learning that she knows it from Gob. Learning the password will require the player to pass a Speech check or use Lady Killer.
 * Note that even if the player comes close enough to pick up GNR's signal near the D.C. ruins, listening in on the station and hearing Three Dog mention James will not advance the quest.
 * The information reveals that James is heading over to the Galaxy News Radio building in downtown D.C. The specific section of the ruins can be difficult to reach, but the most direct way leads through via Farragut West metro station to Chevy Chase. The player will encounter Sentinel Sarah Lyons and the Lyons' Pride in the ruins. After a brief exchange, Sarah will grudgingly allow the player to accompany her unit to the GNR Plaza.
 * If the player already spoke with Madison Li, entered Jefferson Memorial, or found James before arriving at Chevy Chase, the Pride will be long gone. The dead soldier with the Fat Man and eight mininukes will not spawn either.
 * The squad fights their way through the Early Dawn Elementary to the plaza. The running battle culminates in a showdown with a super mutant behemoth, which appears moments after the super mutants are all dead. Initiate Reddin is killed by the exploding buses. The player has the opportunity to collect a Fat Man from the dead soldier at the fountain and use it against the behemoth.
 * The battle is an excellent opportunity to gather spare power armor suits and Brotherhood holotags, for The Outcast Collection Agent and Collecting Holotags respectively.
 * After the behemoth is dead, the player will be cleared to enter Galaxy News Radio and talk to Three Dog upstairs. The DJ will ask for a favor before he reveals where James went off to, which requires the player to complete the quest to restore the broadcasting signal strength's first. The player can instead elect to bypass the requirement with a Speech check and complete the quest later, at their leisure.
 * Using Speech will also make Three Dog offer a different reward for his quest, coordinates to a stash of military ordnance.
 * Once the player has the information, the quest ends and Scientific Pursuits begins.
 * If the player kills Three Dog before learning about James' wherabouts, The Search Continues begins instead.
 * At any point, the player can skip the entire search by making a beeline for Vault 112 and finding James early on. Skipping will not award achievements and trophies associated with the quests that focus on tracking James down.

Bugs

 * The quest may bug out, resulting in the behemoth not appearing and the quest becoming stuck. GNR's doors cannot be opened that way and the Brotherhood soldiers will just wander the plaza aimlessly. Similarly, the game might fail to register that the behemoth was killed. Reloading can help. The behemoth can also spawn, but become stuck, allowing for it to be taken down with ease.
 * The characters' behavior in the area can bug out, causing generic Paladins to attack the player if they enter and leave GNR immediately. Killing them will aggro the remainder of Brotherhood forces.