Marty’s Grandparents?

They might have died when he was young. I've seen photos of my grandparents but they died when I was little so I don't remember them.

Seeing your grandparents, you always only know as elderly in their prime can be also quite shocking/irritating.

Sidha108, Marty wakes in his mother's bedroom, so he knows that his grandparents are downstairs. He, however, has no idea that he is going to meet his parents. Lorraine is a drug addict, her father is a domineering ignoramus, and her youngest brother is in prison. Marty's maternal extended family is riddled with unstable connections, and I wouldn't be surprised to learn that his aunt and two other uncles also have major problems. The boy's mother might have stopped talking to her father and one of her siblings.

He does look around the table at everyone in "I'm in a daze" kind of way but by that point after seeing his mum and dad the shock factor had probably worn off.