Hunter Hunted (Fallout 4)

Hunter/Hunted is a main story quest and achievement/trophy in Fallout 4.

Detailed walkthrough
After receiving the quest, travel to the C.I.T. ruins north of Diamond City. The "courser signal" will be available on the Pip-Boy's radio at that point. Tune to it and follow the signal east to Greenetech Genetics.

Greenetech Genetics is filled with Gunners who are fighting Z2-47, the courser. Upon entering the building, the commander of the Gunners starts issuing orders over the intercom. He orders the majority of his troops to retreat up the building and the rest to engage the Sole Survivor. The player will have to fight their way up through the building. The courser is just ahead the whole time and easily eliminates his opposition, littering his path with Gunner bodies.

Reaching the fifth floor, a salvo of explosions can be heard. Missiles are being fired at the courser (who shrugs them off). These explosions will not affect the player. On the seventh floor, there is an elevator that goes up to the top of the building.

Once there, the courser can be heard threatening some Gunners for a password. One refuses to give it to him and will be executed. One may intervene in time to prevent the rest of the Gunners from being killed. Approach him and he will ask what the Sole Survivor wants; shortly afterward, he will engage the Sole Survivor in combat unless they say the deactivation code obtained from Mama Murphy. Once the fight is over, one can loot the courser chip off his body and the quest is complete.

After the fight, one can see a woman locked in the room that the courser was trying to gain access to. She asks the Sole Survivor to retrieve the password to the door that one of the Gunners stashed in a nearby toolbox. Once she is let out, she reveals that she is a synth (K1-98) and says that the courser was after her and the Gunners caught her as she traveled across the Commonwealth. She will request to leave.

Any Gunners that were not yet executed by the courser will beg to be spared. There are no interactions with them otherwise. If the Gunners are not killed and K1-98 is not released, the Gunners will be missing while K1-98 will still be present upon returning to the building.

Bugs

 * When the player arrives in the elevator room at the seventh floor of Greenetech Genetics, the elevator might not be there. Instead, the player can look through the building and see Boston.
 * This can be fixed by moving to the right of the elevator door (which isn't there), then the option to close the elevator will appear. When the player presses this, the elevator will close and appear to them.
 * In some cases, Z2-47 may immediately attack the player rather than initiate dialogue. The elevators glitch and the game freezes up.
 * Wearing power armor with a targeting HUD or while under the effects of Berry Mentats may cause immediate confrontation on sight, as it does in many other cases.
 * Unlocking the terminal that opens the door to the Commonwealth and walking through the door will "kill" Z2-47, and render his body missing and unlootable.
 * When moving about the building, the conflict triggered by the Survivor's position can frequently cause an instant crash-to-desktop.
 * To remedy, use the command when approaching these locations, and reactivate the AI after reaching the courser.
 * Alternatively, use the command to warp to the courser's location, and finish the quest normally, using the roof access or an area warp to exit.
 * If the courser chip is looted too quickly after Z2-47 dies, the "Kill Courser" stage may not complete, preventing "Recover the Courser Chip" from being marked as complete. Though the quest still completes, this will lock the player out from Dejen's quest, Hunting the Hunter, since the required stage was not completed. To avoid this, wait for "Kill Courser" to be marked as complete before looting the chip.
 * On rare occasions, Z2-47 will be found engaging Gunners en route to the top on the same floor as the player, which may result in him being killed prematurely either by the Gunners or attacks from the player's actions. Although the quest itself is not affected, it may cause difficulty in recovering the courser chip.