George and Lorraine
At the start of Back to the Future we see that George and Lorraine are in a passionless marriage, possibly only living together out of habit, more so than love.
George is still his timid, nerdy self that Martysees when he travels back to 1955 in the DeLorean time machine. George is also bullied by his supervisor Biff Tannen and, despite Biff crashing the McFly family car, George is persuaded by Biff to accept responsibility, owing to his fear of confrontation.
George seems more interested in the television show he is watching whilst eating, than family interaction. His hair is slicked back and is still wearing thick glasses.
Lorraine has become an alcoholic, as demonstrated by her continually pouring herself glasses of vodka. She seems to be carrying a bit of weight, and is out of touch with fashion, as demonstrated by her "dowdy" fashion sense. Lorraine remarks to her daughter Linda that she never "sat in a parked car with a boy", leaving Linda to ask the question "How am I ever supposed to meet anybody?" and goes onto explain how she and George first met.
Dave and Linda
Dave and Linda, the eldest and middle children of George and Lorraine, are also at the dinner table. We see that Linda is single and luckless in love and somewhat depressed, and Dave is working at Burger King with no hope or aspirations of bettering himself.
Lorraine remarks that he should watch his mouth after he curses and then asks him to give her a kiss before he leaves for work, leaving him to exclaim "Damn it mom' make it quick".
Biff
Biff, as we will also see in 1955, still bullies George. He is his supervisior and treats George poorly. He was on his way to the McFly house in George's car, and through his own fault — namely, drinking and driving (at the same time!) — crashed the car, yet still forces George to take responsibility, for not notifying him of the "blind spot" he claims the car had. Biff then forces him to "type up the papers" that would usually be Biff's job (because Biff is either too lazy or stupid, or both, to do them himself), and George duly accepts to take on his supervisor's tasks, for fear of an argument.
Lorraine and George, after Marty's time travel
Marty awakes after returning from 1955, to see Dave and Linda at the breakfast table. This scene will be explained shortly.
Lorraine and George walk in, carrying tennis racquets, signifying that they had been engaging in sports together, possibly with other couples, demonstrating they now have an active social life.
Biff, who was seen to be bullying George, is no longer his supervisor, and now instead runs what appears to be an auto detailing service, and is waxing a new BMW 733i .
Lorraine is slimmer, weight- and fashion-conscious and George is suave, sophisticated and confident. This is demonstrated by him confronting Biff who has claimed he has nearly finished waxing the car when he hasn't.
Biff then brings in a box in to the McFly living room, which contains copies of a science-fiction novel written by George, showing that he had found the confidence to seek the publication of the books he had written in his youth.
Biff after Marty's time travel
Prior to Marty's intervention, Biff is loud, obnoxious and a bully, with a controlling nature over George and a lack of respect for Marty.
After Marty returns, we see Biff is a much quieter man who, after Marty's intervention, has changed dramatically.
Dave and Linda after Marty's time travel
Linda is now seen to have the option of two possible dates, "Greg or Craig", she is eating a healthy breakfast and seems more upbeat, Dave is no longer in a Burger King uniform, and is seen to be wearing a suit.
When Marty asks Dave what he's wearing, Dave replies, "I always wear a suit to the office."
And finally - Marty after his own time travel
While there are no obvious changes to Marty's lifestyle, he is seen walking downstairs, carrying a brown envelope. The Bobs were quoted as saying this could be a demo tape of his music Marty was planning to send off, as he now subconsciously had a new found sense of confidence.
