Final answer:
Apuleius and Psyche in 'Metamorphoses' share the trait of curiosity, which causes them to face significant challenges. This curiosity drives Lucius to become a donkey and Psyche to betray Cupid's trust.
Step-by-step explanation:
In Apuleius' Metamorphoses, both Apuleius and Psyche exhibit curiosity that leads to troublesome situations. Apuleius, through his character Lucius, is transformed into a donkey after his curiosity about magic causes him to meddle with witchcraft. Similarly, Psyche's curiosity compels her to betray her husband's trust, leading to her separation from Cupid. Both characters experience significant trials due to their inquisitive nature - illustrating a shared trait that while providing the initial trigger for their adversities, ultimately paves the way towards their individual growth and realization.