Board Thread:The Flash discussions/@comment-104.238.169.21-20151108090141/@comment-5167151-20151213230715

It makes no sense dramaturgically if Zoom is someone unknown to Barry.

The authors have to surpass the emotional bond between Barry and his mentor Wells from last Season. So Zoom must be a person with a strong emotional bond to Barry thus the unveiling of Zooms identity Barry disturbed and shocked even if this is only the doppelgänger from earth-2 from this person.

so lets look at the possible candidates for this to:

Barry Allen E-2 : possible but too obvious also Barry should not be too traumatized to fight his evil doppelgänger. last but not least would the authors give away the opportunity for introducing Johnny Quick and the Crime Syndicate from earth-3 (what the world is which all known superheroes are supervillains) in later seasons.

Wally West E-2: Barry is not enough personal connected Wally to have remorse to fight against an evil version of him.

Due to the strong theme of fathers and sons in this season (see Joe West and Wally or Barry and Henry or even Captain Cold and his Father Lewis) I go strong assumption Zoom is either Joe West E-2 or Henry Allen E-2.