Board Thread:Off Topic/@comment-27082610-20170729051211/@comment-24534644-20170802040239

@Spirit&Someone: I did account for that possibility. The Semblance will force a target back along the same path previously traveled, meaning it can't be knocked off course while in the process of a rewind. Of course, that's not to say there aren't limits. If the Semblance needs to account for unexpected resistance, then the energy exerted to push an object through will be taken out of the Aura. So is a 3 foot steel wall were to SUDDENLY materialize in an object's trajectory, it wouldn't be able to just straight up punch through it, not without severely draining aura reserves to near-depletion. However, in the case of Grimm and other opponents, it's actually quite handy, as it makes any thrown weapons even more deadly on the return route. Even so, in the event that something appears that would cost too much Aura to go through, Hikari is able to cut off the Semblance effect at any point she desires.

And yes, Someone, if used on another person they ARE aware of what's going on. They're just physically forced to reverse their motions.