Stéphane Moiteret, 42 years old, is accused of murder and acts of torture while his partner Noëlla Hégo, 52 years old, stands accused of complicity.
In the courtroom on Monday, Moiteret appeared scared and was barely audible when he told the judges his name, French weekly Le Point reports.
Psychological experts disagree on whether Moiteret and Hégo are sane and should face trial.
The couple say they are Australian pilgrims on a quest to save the world. Hégo insists on being called "Her Majesty" or "Her Excellency".
The victim Valentin Crémault was found stabbed to death in the town of Lagnieu. He had gone on a bike ride.
The couple Moiteret and Hégo are suspected of killing Valentin after traces of blood containing the child’s DNA were found at a nearby parish where they were staying.
Moiteret insists a look-alike commited the crime.