How we cite our quotes: All quotations are from Back to the Future.
Quote #1
Doc: Now remember, according to my theory you interfered with your parents' first meeting. They don't meet, they don't fall in love, they won't get married and they won't have kids. That's why your older brother's disappeared from that photograph. Your sister will follow and, unless you repair the damages, you'll be next.
Geez, Doc. Lay it on us. Don't sugarcoat it or anything. All right, so Doc is direct and honest, and we can appreciate that. Basically, he's informing us of the first major transformation in the film, which is brought about by Marty bumping into his parents and changing the course of history. This transformation isn't an emotional one, as much as it is a your-hand-is-going-to-start-disappearing-and-then-the-rest-of-you sort of deal.
Quote #2
George: I'm George. George McFly, and I'm your density. I mean…I'm your destiny.
Smooth. George may come across as a tad awkward in the flirtation department, but this is actually a big step up for him. He never would have done anything like this before Marty came along, so he's exhibiting some definite growth. And, lucky for him, Lorraine actually likes "awkward and helpless." As evidenced by her Florence Nightingale issues.
Quote #3
George: No, Biff, you leave her alone.
Whoa. Where did this George come from? The old George would have followed orders from Biff, closing the door and leaving Lorraine to her fate. But the new George has courage, and integrity… and he's growing to like this Lorraine gal. We can already see the formation of a better, more assertive human being.