Hole in the Wall

Hole in the Wall is a side quest in Fallout 4.

Detailed walkthrough
After donating blood to Dr. Forsythe, leave the vault and either pursue the Here Kitty, Kitty quest to find Ashes or else wait for 24 hours or more before returning. (You may have to complete another quest in addition to waiting 24 hours before the next scene will trigger.) Austin Engill will have been moved to the vault's medical bay. Speaking with Dr. Penske begins the quest.

Austin was bitten by a mole rat when wandering in a secret partition of Vault 81 and subsequently fell ill. The player must follow Bobby De Luca to the entrance hidden in the reactor room. They are asked to go into that part of the vault and find a cure. During the investigation, they must fight their way through run-down rooms full of Vault 81 lab mole rats, which will transmit a disease if they manage to bite the Sole Survivor, their companion or any activated protectron, conferring a potentially permanent loss of 10 HP. The true purpose of Vault 81 as an infectious disease incubation and vaccine development facility is also discovered. In the final area there is a terminal that must be hacked or unlocked with a password in the far room on the upper floor past a mole rat brood mother. The password to the locked terminal is next to the research comm terminal in the subsequent room. After this the player finds a robot named Curie who has manufactured the cure; however, there is only one dose left. Curie follows the player out of the secret vault up an elevator back to the locked door by the main vault's entrance. The player must then return to Dr. Forsythe in the medical bay with the cure and make a choice:

Option 1: Give Austin the cure
If the Sole Survivor gives the cure to Dr. Forsythe, they receive rewards including the syringer rifle and a room in Vault 81 located across from the depot. Most items throughout the vault are no longer marked as owned and can be freely picked up without angering the residents. As a side effect, if the player character has contracted the disease during this quest, they keep the disease.

Option 2: Deny Austin the cure
No matter whether it's by directly refusing it in dialogue (requires selecting "Only one, it's mine" followed by "Let him die"), selling or losing it, or using it on yourself (possibly to cure your own mole rat disease), all of these options are treated the same: Austin dies and everyone in Vault 81 blames the Sole Survivor. A small memorial for him is prepared in the classroom under the "America lives on... in you" poster, consisting of a candle, a new teal flared vase, a toy car, a baseball glove and a teddy bear.

Either way, the quest concludes and Curie asks to accompany the Sole Survivor around the Commonwealth in order to further her scientific research, becoming available as a companion.

Companion affinity

 * Cait, MacCready, and X6-88 dislike giving Austin the cure and like keeping it for yourself.
 * Danse likes giving Austin the cure and dislikes keeping it.
 * Codsworth, Preston, Piper, Hancock, and Nick love giving Austin the cure and hate keeping it.
 * Strong likes either outcome.
 * All but two companions (Danse and Deacon) dislike the option to split the cure, "good" companions for being selfish and "evil" companions for offering even that much of it to Austin. Danse doesn't care, and Deacon likes this option, as well as loves giving Austin the full cure and dislikes keeping it.
 * There are no affinity changes for the second set of dialogue after keeping the cure for yourself, whether you back down and decide to give it to Austin after all, or stand by condemning Austin to death, so affinity changes are reflected in the first choice only.

Bugs

 * You can use the cure yourself AND cure Austin by initially saying that you're keeping the cure, backing out of conversation and using the cure on yourself, agreeing to let Austin die, and when given one final chance to hand it over, agree to give the cure to Dr. Forsythe. The dialogue and cutscene will then play out as if you had given him the cure, even though you no longer have a cure to give.
 * If any companion or any type of creature not hostile to the player character, including the hackable protectron in the area, gets hit by one of the diseased mole rats, then the player character will get the disease, as if they had been bitten instead.
 * If you leave the vault before Bobby opens the secret door, he will have gone into the secret vault with the secret door still being closed, making it impossible to finish the quest.
 * Sometimes, the cure will duplicate when picked up by the player, making it possible for the player to cure themselves and Austin at the same time.
 * Sometimes Dr. Penske will not be in the room discussing her grandson's illness with Dr. Forsythe and the quest will not start.
 * This can be resolved by going to Dr. Penske's office, and talking to her there to start the quest.
 * If Dr. Penske has been killed the discussion will never begin causing the quest to become glitched rendering it unable to be completed.
 * When you exit the second elevator, the vault dwellers (and guards) in the area may open fire.
 * Sometimes, even if you decided to save Austin's life, when talking to Neil Freund, he will say "What kind of person lets a child die?"

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