Ender’s Game and Ender’s Shadow.
for the umpteenth time.
JEDIT: …and I just now noticed an error. In Ender’s Shadow, Achilles seems to know that the Buggers have a hive mind, when no one in Ender’s Game (the original novel to which Ender’s Shadow runs parallel) knows about that by that point except Mazer Rackham. It doesn’t break the plot; it just makes no sense.