Oasis (quest)

Oasis is a quest in Fallout 3, which unlocks an achievement/trophy.

Quick walkthrough

 * Find Oasis and talk to Birch.
 * Locate Harold's heart in the sunken chambers.
 * Decide:
 * Apply Laurel's liniment to boost Harold's growth.
 * Apply Birch's sap to stifle Harold's growth.
 * Destroy the heart to kill Harold.
 * Return to Birch.

Walkthrough
The quest is initiated by Tree Father Birch when the player approaches the gates to the Oasis. Birch provides rudimentary information on himself, the Treeminders, and invite the player to enter the Oasis. The player can agree and follow, or decline. In the latter case, Maple will let them in on a subsequent visit.

Meeting Harold
Once inside, the player can talk to Birch for more information. A Speech check will coax more information on Harold out of him, while Animal Friend will allow the player to comment on the abundance of animals.

To progress further, the player has to agree to a purification ceremony. This obligatory step is triggered by talking to Birch and then activating the fountain inside the pavilion, just in front of Birch's throne. A cutscene will take place as the Treeminders bestow their blessings, after which the player passes out.

They wake up in front of Harold inside the Grove. He reveals his tragic story and asks that the player euthanize them. It is possible to kill Harold on the spot with an energy weapon or flames (flamer or Shishkebab), though this is considered evil and will turn the Treeminders hostile.

Otherwise, the player can exit the grove.

Locating the heart
The entrance to the caves is located in the western part of the Oasis. Approaching the entry, the player will witness an argument between Leaf Mother Laurel and Tree Father Birch concerning the course the Treeminders will take. Birch advocates limiting his growth with sap to protect Harold and the Oasis. Laurel believes it is a gift that should be stimulated to grow freely. Both will give the player items necessary to carry out their respective plans.

At this point, the player has to talk to all the other inhabitants of the Oasis (Yew, Poplar, Cypress, Linden, Maple) to unlock their respective quest rewards. This also unlocks additional dialogue options with the inhabitants, giving the player the opportunity to exercise Speech skills and learn more about the Oasis and the Treeminders.

The entrance to the caves is locked with a Very Hard lock. Branchtender Cypress will give the player the key to enter. The interior is fairly linear, though packed with mirelurks of various types. Harold's heart is located at the end of the sunken chambers.

The decision
Interacting with the heart presents the player with three options:


 * 1) Apply Laurel's liniment and boost Harold's growth to help the wasteland recover.
 * 2) Apply Birch's sap and limit Harold's growth to protect the Oasis.
 * 3) Destroy the heart and lay the ancient mutant to rest.

Regardless of the decision made, the player can leave the heart chamber through the damp cave, which leads into Harold's grove. There they meet with either Birch or Laurel, who will react to their decision.

Rewards
The quest rewards depend on the choice the player made and who they talked to before deciding. Talking to Yew and passing the Speech check will guarantee that the player receives Yew's bear charm, regardless of their decision.

If the player applied the sap, they will receive Yew's charm, Maple's garb, and a missile launcher with two missiles from Cypress.

If the player applied the liniment, they will receive Yew's charm, Poplar's hood and Linden's Outcast power armor.

If the player chose to destroy the heart, they will receive the Barkskin perk (at the moment of destruction) and Yew's bear charm.

Bugs

 * If the player does not regain control after forced cutscenes, they can use the console command to restore control.
 * In some cases, the audio files relating to Harold's dialogue can be corrupted. Although this was patched, fan-made fixes are available here and Crash Fix.zip here.