4) Cobalt Blue
Back in season 1, there were a lot of theories that Iris’ boyfriend Eddie Thawne would become a villain – seeing how every member of the Thawne family in the comics has gone on to become a bad ‘un. In the end, Eddie actually sacrificed himself to stop the Reverse Flash, but have we really seen the last of the character?
In his final scene, he appeared to be wearing a talisman around his neck. Such a trinket usually belongs to Cobalt Blue AKA Malcolm Thawne. In the comics, Malcolm is actually Barry’s long-lost twin brother who used a magic talisman in his quest to steal Barry’s life – his friends, loved ones and, most importantly, his speed.
This would definitely fit Eddie, who was always jealous of Iris and Barry’s relationship. No one stays dead on this show either, so it wouldn’t be too far-fetched for Eddie to come back as a twisted version of himself. Going by that easter egg from season 1, maybe this has been the plan all along?