i.Imagine you're in one of those ancient tragedies. Y'know, the ones with prophecies and fate and stuff.
Yeah, I know, prophecy is so last paradigm and considered harmful and so on. Just stick with me here.
Suppose you're walking down the road, minding your own business, and you happen to walk by some two-bit oracle. Then, all-of-a-sudden, their eyes roll back and they speak in the classic deep, inhuman voice of prophecy. It's something about how some horrible event shall betide thee; maybe "thou shalt killeth thine heir" or something similarly cliché. Let's just go with that as an example.
Generally, prophecies are infallible, and this one is no different. Thus, you know with certainty that the aforementioned tragedy shalt come to pass. Maybe thou'll accidentally your child in a sparring match, when you're just simply trying to show them the ropes. Perhaps thine child will commit some unforgivable crime, and you must sentence them to death. Or you just lose your temper with them at the wrong time.
They will die by your hand, is what I'm saying.
However, you're also well-read enough to know how these patterns typically resolve. Subverting a prophecy never works. If you forego the sparring match, your child will die unprepared in battle. If you exonerate them of their crime, ve'll recidivate. Or you just won't be there to save them while avoiding them.
You'd be hoist by your own petard, is what I'm saying.
Thou canst not flee either. Mayhaps if thou runeth to the hills, your child attempts a desperate search, and by a thoroughly bizarre sequence of coincidences you mistake them for a bandit, and realize only when it's too late.
Even if you attempt suicide, your child, unable to live with the grief, will do likewise.
The game was rigged. Fate was the original master of the Xantos gambit.
 Warning: TVtropes