Gustave has taken it upon himself to observe Marion and Sanglain following the death of the Princess and DT.   But KT thinks Gustave is in the city of Marquesas for other reasons. 
If I had known, I would have asked for
¡Si lo hubiera sabido, 
hubiese pedido ayer que
¡Si lo hubiera sabido, ayer habría pedido
Se soubesse, teria pedido