He lived with the Orléans family in the Palais-Royal in Paris, and became close with his aunt, despite her well-known disdain for the king's "bastards".
[11] When the king learned of his son's involvement with the duke's circles, he exiled the Chevalier de Lorraine and several other members of the "congregation".
[12] Hoping to mend the relationship between father and son, his aunt Madame suggested that he be sent as a soldier to Flanders, then under French occupation.
Agreeing with his sister-in-law, the king sent his son to the Siege of Kortrijk, where Vermandois soon fell ill.
He was advised by a doctor that he should return to Lille and recover, but, desperate for his father's love, he remained on the battlefield.
His mother, by then a Carmelite nun under the name of Sœur Louise de la Miséricordie ("Sister Louise of Grace"), was still obsessed with the sin of her affair with the king and said upon hearing the news of his son's death, "I ought to weep for his birth far more than his death".