Oasis (quest)

Oasis is a Fallout 3 quest. It is also an Xbox 360, PC achievement, and a Playstation 3 trophy.

Objectives and Walkthrough
Harold, a special FEV mutant from Fallout 1 and Fallout 2 (one of the only characters to appear in all three Fallouts along with Dogmeat) with a tree on his head which he called Bob, eventually found himself overwhelmed by it and became rooted to the ground during his travels in the Capital Wasteland region. Here he was discovered by several people who began to worship him as a god, and a small and exclusive cult known as the Treeminders began to form in secrecy. Bob began to blossom and many plants grew in this area, which became green with life, a stark contrast to the outer wasteland.

The Ritual
When the player approaches Oasis, Tree Father Birch will ask that the player follow him, saying that "He" has summoned him/her. If agreed to, Birch will unlock the gate to the village and lead the player to an outdoor hut. Birch explains that he is the leader of the Treeminders, and that "He" has summoned the player to the village. Although vague about who "He" is, wishing the player character to find out on their own, a Speech Check may be passed to discover what "He" is. The Treeminders ask that the player drink a sap in a ritual to purge the PC of all evil that might be inside him, so that "He" may go unharmed.

Afterward the ritual, the PC is placed in The Grove, where they meet Harold. Harold reveals his true identity, and begs for mercy; after being stuck in the same position for decades he is eager for death. The other dwellers of "Oasis" have ignored Harold's wishes so far, and ask you to instead either suppress or expand Harold/Bob's fertility.

An argument after leaving The Grove reveals that Tree Father Birch wishes to stop Harold's growth with a sap in order to protect him, and Leaf Mother Laurel wishes to apply a liniment that will accelerate it, to spread his influence to the entire wasteland. The rest of the Treeminders are also converseable at this point, who will express their views on the situation. The main entryway to the cave system is in the main Oasis hub area. The player can either pick the lock (100 Lockpick required) or ask the nearby guard for the key.

Instead of those options, Harold may be burned down with a fire-based weapon. If this is done, the player will receive negative Karma, and all of Oasis will become hostile.

If not burning Harold, speaking with Sapling Yew before going in is recommended. If a speech check is passed in her dialogue, she will give Yew's Bear Charm after completion of the quest, which will give +10 to Speech. The Child at Heart perk can be employed as an alternative to guarantee success.

Into the Caves
Resistance in the Oasis Caverns mostly consists of various Mirelurks, along with the odd Radroach. NPCs will have trouble following through the mess of underwater tunnels, so they should be left outside. Strangely, some dead wastelanders are in here. There's plenty of decent loot to be had in the tunnels, so search extensively.

In order to advance, going underwater is necessary at times, so if it doesn't look like there's a way through, try checking underwater. Near the end of the Sunken Chambers, a thumping will be heard. This is the sound of Harold's heart. When reached and interacted with, several options present themself to the player.


 * Apply Birch's Sap to stop Harold's growth. The reward for doing this is a Missile Launcher with Missiles from Branchtender Cypress, and Maple's Garb from Branchtender Maple
 * Apply Laurel's Liniment to speed up Harold's growth. The reward for doing this is Poplar's Hood from Bloomseer Poplar, and Linden's Outcast Power Armor from Branchtender Linden.
 * Destroy the heart. This will expose the player to Harold's mutation and grant the player the Barkskin perk which grants 5% Damage Resistance.

A nearby door will lead into another subcavern, which will lead back to the Grove, where either Birch or Laurel will be waiting depending on your choice. If the heart was destroyed, Birch will be there, and express regret over not listening to Harold.

Rewards
In addition to the mentioned rewards, Sapling Yew will give the player Yew's Bear Charm if the Speech Check was passed before making the decision. She will give it regardless of the choice made, unless the player burned Harold. The Treeminders may be spoken to after this to get dialogue about your decision. Harold also has some more dialogue about your choice, if you chose not to kill him. If the player chose not to kill Harold, they may still burn him after getting the rewards.

Bugs

 * If Tree Father Birch is killed, all of Oasis will turn hostile against the player. However, this happens even the player wasn't the one to kill him (e.g. an enemy was lured over before starting the quest). Strangely, the same won't happen if Branchtender Maple is killed in this fashion.
 * If the player does not stand across from Tree Father Birch during the ritual, it may not complete correctly, effectively forcing the player to reset.
 * Occasionally, Oasis will be locked for no given reason. If this happens after starting the quest but before finishing it, it will be impossible to complete. This will also effectively cause Birch's Sap and Laurel's Liniment to permanently take up weight in the player's inventory. On very rare occasions, it is even possible for the door to lock while INSIDE Oasis, although in that instance, it is possible to escape if Tree Father Birch is killed and the Key to Oasis is retrieved from his body.
 * The Burnmaster is not considered a fire weapon by the game and will not burn Harold.
 * When approaching Birch and Laurel after seeing Harold, if the player gets close enough so they can hit them with a melee or unarmed weapon in V.A.T.S., but not close enough to trigger the conversation, and tries to attack either in such a fashion, the first two lines of their argument will take place in slow motion with a shaky camera.
 * Telling Fawkes to wait in the cave while the PC completes the quest may cause the game to crash or freeze when the player attempts to reenter the cave.
 * The ledge in Damp Cave leading to Harold's heart can be reached from The Grove's side. Inside, there is a Mirelurk King and two Mirelurks waiting. Kill the Mirelurk King and one of the Mirelurks, and get the remaining Mirelurk's attention. Then, scale the cliff near the door to the next area, starting from the rocks on the right side (not the little shoreline just below it). The Mirelurk will mysteriously teleport on top. Get its attention again if it was lost (i.e. a Stealth Boy was in use), get as close as possible, then go into V.A.T.S. and try to hit it. The player character will teleport onto the cliff as well to attack the Mirelurk. However, the door will require a key to open.
 * Sometimes, Sapling Yew will not offer you her charm, even if the Speech Check/Perk Check is completed.
 * If the Treeminders are angered through dialogue, the cave may still be entered with 100 Lockpick. The heart can still be reached, and the Barkskin perk can still be obtained. Strangely, the Sap or Liniment can be applied despite not having either. Harold will react accordingly through dialogue to this. However, as the only way to complete the quest is to speak with Birch/Laurel, and they will only say to leave when spoken to, again, Harold must burn if the quest is to be completed. If the Barkskin perk is obtained, Harold will not be able to be burned, leaving the quest permanently incomplete.