How to unlock: You need to perform an action that results in your becoming the enemy of the Institute.
- Return to the Institute
This quest can be activated in many different ways, where in general, you need to perform an action that makes you the enemy of the Institute. It may be, for example, murdering Father or one of the Institute's employees, or take a quest that goes against the Institute's interest (e.g. side with Minutemen in Pinned or warn the Brotherhood of Steel after you receive the Mass Fusion quest). If you have not performed such an action on the grounds of the Institute and Father is still alive, you can fast-travel there and listen to his short speech, where he confirms that you have actually become enemies and that this is the last conversation you two have.
Quest rewards: Experience points