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. 
Those you left behind 
will never forget you.
Esos que dejaron atrás nunca los olvidarán.
Aquellos que dejaron atrás nunca los olvidarán.
Aqueles que vocês deixaram, jamais
se esqueceração de vocês.