Le Gros thrived on playful invention.
When, some time between 1706 and 1715, he was asked by the Portuguese ambassador to add heads, hands and legs to a fragmented antique group of Amor and Psyche, he deliberately turned the love story on its head and transformed it to the tale of Caunus and Byblis in which Caunus vehemently defends himself against the sexual advances of his sister.
Le Gros' creation quickly became popular and triggered a rafter of drawings, reproductions and copies by for example Pompeo Batoni, Francesco Carradori, Martin Klauer and, best known of all, Laurent Delvaux who carved two marble versions.
Le Gros' work soon ended up in Germany where several plaster casts were made.
Some time later it was purified back to Amor and Psyche but later destroyed in a fire.
The most faithful impression of what it looked like is the plaster cast in Tiefurt House near Weimar.

In 1708–10 Le Gros collaborated with his close friend, the architect Filippo Juvarra, in the creation of the Cappella Antamori in the church of San Girolamo della Carità, Rome.
His statue of San Filippo Neri is set against a large backlit coloured glass window and seems to dematerialise in the warm yellow orange glow.
Drawings by both Le Gros and Juvarra demonstrate that each of them contributed to finding the right composition for the sculpture and tried a number of different poses.
Le Gros also made many putti and cherubim and two plaster reliefs for the ceiling showing scenes from Neri's life.
The exquisitely crafted chapel is one of the very few traces of Juvarra's activities in Rome.

With the vast, lavish Monument to Pope Gregory XV and cardinal Ludovico Ludovisi in Sant'Ignazio, Le Gros conceived his last work for the Jesuits between about 1709–14.
It singularly combines the tombs of both the pope and his cardinal-nephew and celebrates their merits from a pronounced Jesuit point of view as the inscription explains: ALTER IGNATIUM ARIS.
ALTER ARAS IGNATIO (one raised Ignatius to the altars, the other erected altars for Ignatius).
This alludes to the facts that Gregory canonised the saint and Ludovico built the church of Sant'Ignazio.
The concept is highly theatrical with a large curtain (made from coloured marble) being drawn back by two Famae (both the work of Pierre-Étienne Monnot from designs by Le Gros) to reveal the protagonist.
This curtain obscures the wall behind and creates the illusion that the monument has the rare quality of being free standing rather than attached to the wall as is the norm.
The composition also makes use of the monument's location in the only chapel with a side entrance to the church (to the right of the monument) by turning several figures directly towards visitors entering from there and inviting them in – an effect which today is hard to appreciate as the door is no longer in use.

From 1711–14 followed the Cappella di S. Francesco di Paola in San Giacomo degli Incurabili, for which Le Gros was the architect  – which basically means he was in charge of all its decoration – and the sculptor of a large relief showing the saint in adoration of an old venerated image of the Madonna and child, intervening to cure the sick.
Le Gros thrived on playful invention. When, some time between 1706 and 1715, he was asked by the Portuguese ambassador to add heads, hands and legs to a fragmented antique group of Amor and Psyche, he deliberately turned the love story on its head and transformed it to the tale of Caunus and Byblis in which Caunus vehemently defends himself against the sexual advances of his sister. Le Gros' creation quickly became popular and triggered a rafter of drawings, reproductions and copies by for example Pompeo Batoni, Francesco Carradori, Martin Klauer and, best known of all, Laurent Delvaux who carved two marble versions. Le Gros' work soon ended up in Germany where several plaster casts were made. Some time later it was purified back to Amor and Psyche but later destroyed in a fire. The most faithful impression of what it looked like is the plaster cast in Tiefurt House near Weimar.
In 1708–10 Le Gros collaborated with his close friend, the architect Filippo Juvarra, in the creation of the Cappella Antamori in the church of San Girolamo della Carità, Rome. His statue of San Filippo Neri is set against a large backlit coloured glass window and seems to dematerialise in the warm yellow orange glow. Drawings by both Le Gros and Juvarra demonstrate that each of them contributed to finding the right composition for the sculpture and tried a number of different poses. Le Gros also made many putti and cherubim and two plaster reliefs for the ceiling showing scenes from Neri's life. The exquisitely crafted chapel is one of the very few traces of Juvarra's activities in Rome. 
With the vast, lavish Monument to Pope Gregory XV and cardinal Ludovico Ludovisi in Sant'Ignazio, Le Gros conceived his last work for the Jesuits between about 1709–14. It singularly combines the tombs of both the pope and his cardinal-nephew and celebrates their merits from a pronounced Jesuit point of view as the inscription explains: ALTER IGNATIUM ARIS. ALTER ARAS IGNATIO (one raised Ignatius to the altars, the other erected altars for Ignatius). This alludes to the facts that Gregory canonised the saint and Ludovico built the church of Sant'Ignazio. The concept is highly theatrical with a large curtain (made from coloured marble) being drawn back by two Famae (both the work of Pierre-Étienne Monnot from designs by Le Gros) to reveal the protagonist. This curtain obscures the wall behind and creates the illusion that the monument has the rare quality of being free standing rather than attached to the wall as is the norm. The composition also makes use of the monument's location in the only chapel with a side entrance to the church (to the right of the monument) by turning several figures directly towards visitors entering from there and inviting them in – an effect which today is hard to appreciate as the door is no longer in use. 
From 1711–14 followed the Cappella di S. Francesco di Paola in San Giacomo degli Incurabili, for which Le Gros was the architect  – which basically means he was in charge of all its decoration – and the sculptor of a large relief showing the saint in adoration of an old venerated image of the Madonna and child, intervening to cure the sick.
Pierre Le Gros the Younger