Phyllis was a settler of the Commonwealth together with her grandson Samuel sometime before October 23, 2287. After her daughter's death, she managed to gain entry into a farm where she worked to keep herself and Samuel sheltered. One night when she was on watch, she blacked out and only came to upon hearing a gunshot, finding herself standing in front of her grandson's blood-covered body with a gun in her hand. When the other settlers heard the shot, they came running and later told her that they saw nobody but Phyllis at the time.
Believing that she killed Samuel, Phyllis concludes that she must be a synth controlled by the Institute and that she lost control because she was given an order to kill. She believes that at any moment, the Institute could make her kill again, and has decided to lock herself away for everyone else's safety.
As she does not drop a synth component if killed, and her log reveals that she has suffered from violent nightmares for some time, it is implied that Phyllis simply fell asleep while on watch and accidentally shot her grandson. Believing she is a synth has been her coping mechanism.
Piper will like questioning Phyllis, and will like it if you ask Phyllis to join the Minutemen. Paladin Danse will dislike sparing Phyllis, but will still love it if she is killed afterwards. Curie likes it if she is persuaded into joining the Minutemen. Cait likes killing her, but will not dislike sparing her. MacCready likes telling her about Shaun, and will not dislike sparing her. Strong likes killing her, but dislikes the "Anything else?" found deep into the friendly dialogue. Nick Valentine likes telling her about Shaun, and telling her that she might be a synth, but it doesn't matter. X6-88 dislikes asking "Anything else?", or being evasive at the end of friendly dialog, and He hates telling her about Shaun. Despite this, he neither likes nor dislikes killing her.
If spared, Phyllis will eventually write a letter to the Sole Survivor thanking them and explaining that she needs to move on. The contents of the letter vary slightly depending on the dialogue options chosen when first speaking to her.
If killed at the settlement, her body will eventually disappear.
If the player character is allied with the Brotherhood of Steel, then an additional speech option will be given saying that it is their duty to purge her after hearing her claim that she's a synth, causing her to become hostile.
ps4 Upon arriving at Egret Tours Marina for the first time, Phyllis may immediately attack the Sole Survivor. Killing her will still give the access to the settlement.[verified]
pcps4xboxone After talking with Phyllis when first arriving, then receiving a misc quest update from her terminal upstairs about Samuel, Phyllis may confront the Sole Survivor about "messing with [her] stuff" and subsequently repeat the entire initial conversation as though it didn't already happen. Companions may also react to the conversation again, even if the same options from the first time through (now faded in the UI) are chosen the second time.[verified]
ps4pcIf she is the quest giver for a Minutemen settlement quest for Egret Tours Marina the mission may be unable to complete. As she is a unique character with her own voice she does not have the settler dialogue required to complete the mission.[verified]
One may be able to receive and turn in the quest even though it seems as though the dialogue isn't progressing. Subtitles may appear if turned on, and though it seems to take longer than normal dialogue, the game may act as if it is despite her complete silence. However, while the quest can be initiated, it cannot be completed unless she is confronted about Samuel; as speaking to her will yield no caps reward. Alternatively, you can simply talk to another settler in order to satisfy the requirements of the quest and get the cap reward.