User blog comment:Bo-Katan/Thawne and Time Remnants/@comment-3221148-20171207123542

"He got erased by Eddie, and then a younger version shows up in 2016 even though in his timeline The Flash didn't exist in 2016"

Yes, in the original timeline the Flash didn't exist in 2016. However, now that Thawne changed it and created him much earlier, a version of him HAD TO meet Barry Allen and start their rivalry earlier, hence the time remnant. Think of the latest episode of Legends, where we see little Lily Stein living with Martin and Clarissa, even though originally she didn't exist, but now the revisited version of the timeline has them interact, and old Stein's (RIP) memories were changing accordingly. This Eobard was a "proper" time remnant, who was fulfilling his time travel destiny and shouldn't have been stopped.

"And then Barry creates Flashpoint, but then lets Eobard fix it. But then instead of fulfilling his destiny as Wells, Eobard takes Barry to the present and goes on to create the Legion of Doom. But his life as Wells still happened to everyone else and he remembers it?"

This is a bit hardler to explain, but, yes, that Eobard somehow got Wells memories even though he never lived as Wells. Presumably, the "flash" of images we see when Thawne was taking Barry back to 2016 through the Speed Force has given both speedsters memories regarding the post-Nora'sDeath timeline. This Eobard was a "plucked out" time remnant, like with Savitar, and other Barry's and Hunter's remnant, moved out of his timeline for convenience, and thus hunted by the Time Wraiths/Black Flash.

"But then Black Flash erases him again, but then he somehow shows up again for Crisis on Earth-X. I'm so confused."

The writers just didn't bother to explain it so far beyond "lol time travel lol".