Dependency

 is a quest that can be obtained in the Commonwealth in Fallout 4.

Synopsis
A druggy influenced by his own twin sister, Bobby is now passively attempting to kill himself through drug use, due to the guilt he feels over the consequences of his recent actions. Guilt-ridden as well, for her part in his self-destruction, his twin sister Tina is looking for a way to save him.

Walkthrough

 * 1) After saving the vault from the viral mole rat experiments, Tina will approach the Sole Survivor in an attempt to get her brother to kick his drug habit.
 * 2) The Sole Survivor will then need to speak with Bobby, in order to convince him to either quit cold-turkey, start a rehabilitation program with the Vault's doctor, or to basically kill himself by overdosing on drugs.
 * 3) So long as Bobby is convinced to stop taking drugs, Tina will thank the Sole Survivor for all of their help, and will mention that this will be a good chance for them to go out into the Commonwealth and find their way.
 * 4) Should a Speech check be passed, Tina and her brother can be convinced to join one of the Sole Survivor's active settlements.

Bugs

 * While it is possible to successfully convince Tina to join one of the Sole Survivor's settlements, the game will immediately register as the Sole Survivor having failed it, immediately after Tina finishes her original dialogue. This effectively makes it impossible to get Tina to leave the vault, as two-way dialogue can no longer be instigated with her.