Tonight's episode of The Flash, titled "Once and Future Flash," dealt with the consequences of what might happen to the future if Barry fails to save Iris West from death at the hands of Savitar later this season.
The world in "Once and Future Flash" was a radically different place, and there wasn't much hope offered as to how they might make the future better.
What exactly is on the line if Barry doesn't manage to save Iris on May 23? Read on...
This is a big one.
After that, she hurt or killed almost everyone in the group, including freezing and destroying Cisco's hands, causing him to lose his powers.
HR & JULIAN
H.R. Wells and Julian Albert are pretty much living a lo-fi verison of their old lives.
Julian has a somewhat more depressing job, and feels lost because he's responsible for Caitlin's transformation and everything that came after -- but more than anything, he's seemingly obsessed with curing/fixing Caitlin...which is something Killer Frost is not interested in.
Joe West lost his whole family as a result of Iris's death and the fallout; Barry distanced himself from everyone he loved, while Wally tried to go after Savitar himself and ended up in a catatonic state.
Joe hated the way Barry abandoned him, and more or less lost faith in his adopted son, until the younger version of Barry showed up to remind everyone what's actually important.
Cisco didn't lose his idealism, but he did lose his friends, his direction, and his powers.
After a fateful encounter with Killer Frost -- the same one we've seen flashes off throughout the season -- Vibe lost his powers when his arms were frozen, breaking off at the wrist; apparently his hands were necessary for the powers to work.
He didn't abandon science, or hope, though, and it's Cisco who helps put everyone back on the straight and narrow path.
All we really know is that after Iris's death, as the team fell apart around him, Wally lost his patience for Barry's attempts to stop Savitar and went after the self-proclaimed Speed God himself, getting badly injured and nearly killed.
Barry Allen was a beacon of hope until he lost Iris.
After her death, he became a shadow of his former self, allowing villains to take over his town and he gave up on everyone around him -- including the concept of The Flash -- allowing everything to come in second to his quest to bring down Savitar. Eventually he succeeded, but by then there wasn't much else left for him to live for.