Parallels between Diane and Jim
It's interesting how many similarities I've found in them:
Their family is the light in their lives
"Henry, you are my sunshine in the darkness" - Diane's words in Episode 3
"Lisa and Larry were the light of my life" - the Vestige of Jim in Episode 5After the loss of Jim and Diane, their children carried with them an item connected to their parent. Larry had Jim's old lighter and a part of Sal's prosthetic was pink, Diane's favourite color.
Sal and Larry primarly blamed themselves for the death/departure of their parent.
Diane and Jim sacrificed themselves to protect their family from the cult and both died in 1984
Also it's worth mentioning that we can find one page from Jim's journal through the puzzle related to Diane's name. And Sal can unlock his last memory about her in Jim's lab.
I think Steve wanted to show how similar Diane and Jim could be with these details and how similar pain Sal and Larry feel from the loss of their parents.