At their best, video games are such massive, sweeping experiences that players can't really be blamed for failing to do everything, be it complete every single side quest or pick up on every last morsel of story and character development.
Sometimes developers decide to sneak important information into optional missions, post-credits scenes you had no idea existed, or simply the wider context of the story.
To that end, you probably didn't realise the grim fates most certainly endured by these characters - from those infected with deadly pathogens to those who got totally stranded in the middle of nowhere forever more, and those who are about to get themselves in a whole heap of trouble.
At a superficial level many of these characters may have seemed totally fine the last time you saw them, but if you think a little harder about their future, or just stick around for a pesky post-credits scene, you'll learn the more unsettling truth of the matter.
Be warned, though: once you learn what happened to these characters, you might wish that you could un-learn it, so proceed with caution...
10. James O'Brian - Days Gone
Throughout Days Gone, protagonist Deacon St. John becomes uneasy allies with James O'Brian, a member of the shady National Emergency Restoration Organisation (NERO).
During the main game players never actually see what O'Brian looks like because his physical appearance is concealed beneath a hazmat suit and mask, but those who keep playing after the linear campaign is completed will eventually unlock a very revealing secret ending.
This ending sees O'Brian once again make contact with Deacon, where he finally removes his mask to reveal that he is in fact infected with an evolved strain of the Freaker Virus which grants him superhuman abilities while maintaining his mental faculties.
While this clearly sets up a sequel where Deacon will battle a new evolved breed of Freakers, it doesn't paint the rosiest future for O'Brian.
With the stability of this strain of the virus totally unknown, it's wholly possible he will eventually devolve into a traditional "dumb" Freaker.
And even if he doesn't, there's still so much up in the air about how he became infected and his relationship with the NERO higher-ups that it's difficult to picture him being long for this world.