Too late for Spoiler Alert...Eobard Thawne (for some reason looking like Harrison Wells) is the Dark Flash on Earth-X. You read that right, not Reverse-Flash, but the Dark Flash.
Could we be seeing a dynamic duo come to life after this crossover between Sara and Alex? Probably not at least regularly since they live on two separate Earths.
She was my sister. I couldn't be angry because she was dead. I couldn't grieve because I was so angry, that's what happens when your sister dies while screwing your boyfriend.