Annette is a commander of the Invaders who spearheads their invasion of Earth and a playable character and villain in Metal Slug Attack. She is also the older sister of Odette but prefers to keep their relationship a secret from the Invader military so she isn't seen as spoiling her. The only other person who knows of their connection is Nowan.
Signs of Curse
Annette makes her first appearance in "Signs of Curse" where she fights off the cursed Ptolemaios and his Ptolemaic Army Special Forces and kills the cursed Ptolemaios right as her sister Odette shows up.
Fall of Disaster
Annette goes on another mission to Earth to see how the Amadeus Syndicate would respond to an attack. To assist her mission, the Invader High Command sent Schwarz Metzelei to accompany her, though Schwarz initially tried to eat Annette when she arrived. The two then commence their mission and attack the Amadeus Syndicate. After a while, Annette obtains what the Invaders wanted and tells Schwarz they are heading back, but Schwarz was to busy enjoying the food of Earth to leave. Annette then threatens to leave her on the planet, causing Schwarz to comply and go back with her.
What I Need to be Myself
Annette receives a distress call from Odette saying that she and Nowan have been captured by the Rebel Army, who intend to experiment on her. Annette attacks the Rebel Army and frees Odette, only to realize that she is actually Nowan mimicking her. Allen Jr. then sends the Emain Macha after them, but Annette destroys them. Annette and Nowan go to pick up Odette and escape back to the Invader homeworld with her. Nowan later asks Annette how she was able tell that she was not Odette, to which Annette that there was something small but special that they lacked.
Fall of Disaster
Annette appeared to assign Nowan a mission to go to Earth with Schwarz Metzelei. Despite her fear of Schwarz, Nowan accepts though Odette expressed concern to her sister that Nowan was behaving unsually.
In the Secret Ending, after being left behind on Earth by Odette and Nowan, Schwarz radios Annette to request a transport but Annette, angry at Schwarz for attempting to eat Nowan, hangs up and leaves her on Earth.