not to me? either you loop time or you shift its direction? pretty sure merlin did both. created a loop in which he created DR and altered time by creating DR. the only thing this does is create parallels in which he never made DR and 'prime' in which he did. the only time travel mechanism i don't believe applies is paradox, for the same reason odin gives, we're still here. it seems a given warlocks used to muck with time pre-WC so i'd imagine 'paradox' would have happened if it were possible, or it did
The whole point of the loop/bridge time-travel concept proposed here is that there wouldn't be a time where it didn't happen.
From Uriel's perspective, time is not linear. Stand back far enough, and it's apparently wibbly wobbly. By creating a permanent temporal bridge, those 5 times are linked to occur at the same time the first time. There was no time he didn't make the prison.
Picture a piece of string. It's linear, as mortals see time. Now imagine that Merlin got help creating a loop, where two parts of the string overlap, like this:
Where the string overlaps itself is two separate points of time. Now imagine a pin getting pushed through the string, bonding the two points together. That makes them permanently bound together. Only instead of just one loop for two points, there are 4 loops for 5 points of time.
The reason Ms Duck has an issue with it is because messing with time like that would seem to be a very high-level trick. She thinks that it would take a WG-level talent to do it.
But Merlin clearly did it, presumably with help. We can either assume that TWG helped, but if so, why did TWG both involving a mortal at all? Or we can assume that one or multiple lower-tier powers (Mab, Odin, Uriel) worked together to do it.
We know that the Ladies working together were able to channel their attack across multiple times. So the idea that there are time-travel capabilities among the powers isn't outrageous. By nature, Mab should be more powerful than Maeve in that aspect.
Again, the theory breaks down at
why do it. There was clearly a major, reality-level
need for Merlin to create the DR prison. If it's as difficult as Duck suspects, then it would require a reality-level need for Harry to go back. And I can't think of one.
But if it doesn't take as much power to create a single bridge, and there were a really-really-important-reason for him to go back, then Mab and others might work together to get it done. I still don't know
why, though.