

That's a strong possibility, since he was freed at the end of The Flash season 5. The Nash Wells twist still doesn't explain the different versions of Harrison Wells, but it does appear that whatever they are, they're trying to warn Nash that Reverse-Flash - who still wears the face of Harrison Wells - is coming back. It doesn't necessarily mean that Nash was seeing Reverse-Flash all along, but it does mean that Reverse-Flash is re-entering the story. His appearance serves as confirmation that Reverse-Flash has something to do with this storyline. As his face changes and his eyes turn red, he says, " He is coming". Nash begins seeing a different Wells, and at the end of the episode, the alternate Wells grabs him.

In The Flash season 6, episode 13, titled "Grodd Friended Me", it's revealed that Reverse-Flash is deeply connected to what Nash is seeing. Related: The Flash Brings Back A Season 1 Villain (Thanks To Crisis' Changes) "Crisis on Infinite Earths" left the Arrowverse with only one Harrison Wells, so Nash knew it shouldn't have been possible for there to be another Wells on Earth-Prime. Nash tried to find Harry's diary, so that he could find out if Harry was still alive. In the following episode, it became clear that only Nash could see Harry. This seemed impossible, considering that Harry and his daughter Jesse seemingly died when Earth-2 was wiped out by a wave of antimatter.

In a recent episode of The Flash, Nash saw a glimpse of someone who looked like Earth-2's Harrison Wells, Harry, but he disappeared immediately. The final scene of The Flash season 6, episode 13 reveald that the visions or hallucinations experienced by Nash Wells (Tom Cavanagh) are related to the Reverse-Flash in some way. The latest episode of The Flash season 6 confirmed that Reverse-Flash is returning to the series.
