I wrote that Marc was carrying Nathaniel in his arms because he was dead tired, but I think that left it more to the freedom of other heads, at least in mine I carry him and took him to his house and then he left.
Don't ask me how, but that talk does help Nathaniel get free from the akuma, although he's left exhausted. Marc helps him go home, and that's where it all ends. The heroes had already arrived by the time the butterfly had fled.