IIRC they were reminiscing about the past and how the place they were in reminded them of Empress Marianne's palace...and their days playing with both Lelouch and Nanaly (or Nunnally, if you want). Then Cornelia vows to pacify Area 11 because they have already lost three siblings to this colony: Clovis, Lelouch and Nanaly (the latter two having faked their deaths during the invasion and seeking shelter at their erstwhile supporters, the Ashfords).
(no subject)