I think we will definitly get to learn more about Fred in season 5, even after his death. We merely learned he "killed" someone in a car accident and that he has a scar relating to it, and boom, he dies. This definitly means his background is deeply connected to the plot in some sort of way, espically since no one brought it up again in the series (unlike how Barb's death was taken by Nancy). I feel like people barely talk about Fred, even though there is something wildly suspicous and mysterious about his past, that I hope will eventually be revealed in season 5. I just feel like people should talk more about him, yk?