Left behind is a holodisk in Fallout 3.
Location
The tape is found on a dead wastelander (baseid 06553F) just east of the Dunwich Building.
Transcript
The others left me! They fucking left me behind!
Okay, I can understand them getting angry because I wandered off. But I thought I saw someone trailing us, so I went to check it out.
Turns out I was wrong. But I was only gone for like ten minutes! They didn't have to leave me behind. I have no idea where they went, but I guess I'd better get up off my ass and try to catch up.