Complex sentence: Once he had matured, Giegue was tasked by his people to make sure that PSI never spreads onto Earth, but he doesn't want to betray those who have raised him, particularly Maria, whom he loved.
Split into simpler sentences: Once he had matured, Giegue was tasked by his people to make sure that PSI never spreads onto Earth. But Giegue didn't want to betray those who raised him, particularly Maria, whom he loved.