In Fallout 4, engaging with non-hostile NPCs or faction members through an attack can have significant consequences. The initial response from the attacked NPC is generally immediate; they will often turn aggressive and initiate combat. If the NPC belongs to a particular faction—such as the Minutemen, Brotherhood of Steel, or the Railroad—the repercussions can escalate even further, leading to the entire faction becoming hostile towards you.

The hostile status conferred upon you from an unprovoked attack is typically temporary, lasting about an in-game day on average. However, the duration can vary based on the specific location. For example, in places like Diamond City, the aggression may subside within approximately one in-game day, whereas in Goodneighbor it might take a few days for NPCs to return to their previous friendly state.

To alleviate hostility, you have a couple of options available. The first is simply to avoid the area where the hostility occurred; over time, as the in-game clock progresses, NPCs may forgive your transgressions and revert to a friendly disposition. If you’re playing on PC, you also have the alternative of using console commands to directly change the NPC’s disposition, effectively resetting their attitude towards you without the need to wait.

It is worth noting that although this mechanic resembles actions from other games, such as the Friends cantrip in Divinity: Original Sin 2—where NPCs can become hostile once the effect wears off—this behavior is distinctive to the structuring and gameplay of Fallout 4.

In summary, while attacking a non-hostile NPC in Fallout 4 can provoke immediate and sometimes severe backlash, the repercussions are generally reversible by allowing time to pass or utilizing cheats, unless the aggression stems from quest-critical actions or specific scripted events. This system emphasizes the consequences of player choice, encouraging reflection upon interactions within the game’s complex world.