[Marty has accepted Tannen's challenge to duel]
Seamus McFly: You had him, Mr. Eastwood! You could have just walked away and nobody would of thought the less of you for it. All it would have been was words... hot air from a buffoon. Instead, you let him rile you, rile you into playin' his game, his way, by his rules.
Marty McFly: Seamus, relax, I know what I'm doin'.
Maggie McFly: He reminds me of poor Martin.
Seamus McFly: Aye.
Marty McFly: Who?
Seamus McFly: Me brother.
Marty McFly: Wait a minute, you have a brother named Martin McFly?
Seamus McFly: *Had* a brother. Martin used to let men provoke him into fightin'. He was concerned people would think him a coward if he refused. That's how he got a Bowie knife shoved through his belly at a saloon in Virginia City. Never considered the future, poor Martin, God rest his soul.
Maggie McFly: Sure'n I hope you're considerin' the future, Mr. Eastwood.
[she walks away]
Marty McFly: [to himself] I think about it all the time.