Time remnants! Possibly the most highly debated and confusing aspect of The Flash’s second season, are they explainable?
While there is no definitive (from the show runners) answer to the question posed above, we’ve here at The Arrowverse have crafted a relatively full circle explanatory theory regarding time remnants and the rules they must follow.
Based on the events of The Flash’s second season it stands to reason that their are two distinct types of time remnants, and one possible exception to both types:
The Two (Two and a Half?) Rules
The Time Remnant from the Future: If your future self is the remnant then he’s free to kill, because the future is in flux, if he helps you out, then you have no reason to go back in time and help your past self out…and so a new future is created. (i.e. Zoom and Barry’s time remnants in the finale).
The Speed Force Protected Time Remnant (Past and Future): If either your past OR future self is the time remnant than being within the Speed Force – as they said in 2×11 – will protect you “like a bomb shelter”, that said, this process effectively would make you a time remnant as well. (i.e. What Zoom may have used in 2×01/2×02 and 2×13/2×14).
The Kill Yourself Exception?: In the finale, after having killed his time remnant, Zoom tells Barry, “you see Barry, there could be two of you, you just have to be willing to kill yourself”; which potentially sounds like a loophole to all established rules of being a time remnant. Potentially, what Zoom is saying is that regardless of whether the secondary version of oneself is from the past or future, as long as one version kills the other version, the timeline isn’t effected.