I Forgot to Remember to Forget

 is a quest in Fallout: New Vegas.

Quick walkthrough
Once you have done enough quests with Boone to gain his loyalty (I am unsure how many this is, but it may be related to killing a certain number of Caesar's Legion - he talked to me about it after wiping out everyone in The Fort), he is willing to talk to you about Bitter Springs. You can suggest going there, but at first he will say no. Later on, however, he will talk to you again, and request that you do go. Once you get there, he asks you to go to the point he was stationed, where he tells you exactly what happened during the Massacre there. He then asks you if you don't mind staying there overnight. If you say yes, the screen will fade out and fade back in, with Boone telling you that a Legion raiding party is on the way. You must then defeat the Legionaries to save Bitter Springs. Once they are all dead, Boone will talk to you again, and at the end of the conversation his armour is upgraded.