I agree it can get really bad if poorly done, but there are actually 5 temporal paradoxes: 1) Causality (Cause comes before effect- ie. In the flow of time, the effect (Emma) would exist before the cause (her birth). 2) The grandfather paradox (You change the past but you’ll instantly feel the alteration, as will your ancestors). 3) Consistent causal loop (You can travel back, but you always did, so nothing changes). 4) Distorted probability (You can travel back but you can’t change anything). 5) Parallel universe (You can change the past, but you’ll just create a brand new timeline). & that’s where I have problems with it- it’s not much of a story with 1, 2, 3 or 4 IMO either. #5 can be very interesting when done right- but then who’s really who & it can get messy fast!