Let's say Eobard Thawne is a good person (You will not believe i know) He changed the entire arrowverse(Not only the flash)timeline to prevent the crisis from destroying the multiverse.
I think about this every day becoz he has no reason to be a bad guy.
And he also said that time travel revealed him some secrets
And I believe that his purpose is to change the timeline accordingly to help the heroes win in the Cirsis and save the multiverse.
You guys may think i am a little insane but this can also be true (0.01%)