You let someone in. They know the way. They know how to open this door, how navigate this maze. Ariadne may hand Theseus the golden thread, but it is not hers to give; the thread belongs to him whose fate it is to receive it. Of course, once his wretched monster is slain, Theseus eventually abandons Ariadne. And she eventually hangs herself. Arguably, this too is Fate. The real villain in any Greek tragedy, one may say, is not the gorgon or the titan, the fickle god or the flawed mortal.
It is always Fate.