Despite being a high-profile family in Anno Domini era, not much is known about the history of the Corner family. They held the position of Celestial Being observers for generations but have also secretly planned to betray the organization and take over the world. A golden opportunity for their ambitions arose 80 years before the Gundams' armed interventions when a team belonging to the Corner family, in guise as a UN exploration team, retrieved a purple Haro back from a desolate Europa research vessel at Jupiter. The Haro contained information about the creation of the GN Drives, giving the family the opportunity to build their own solar furnace, the GN Drive Tau.
The creation of GN Drive Tau brought forth the development of the Corners' GN-powered mobile suits and the training of pilots to operate them. The Corners' ambition inspired a vision of a hero that would be revered by the world after defeating the Gundams and Celestial Being. It is because of this that family heir Alejandro Corner was also trained to be a mobile suit pilot besides being educated in political science.
Alejandro eventually took the role of heading the family, posing both as a UN Ambassador and a Celestial Being observer. Alejandro hired mercenary Ali al-Saachez to do the work behind the scenes. By forming an alliance with another observer, Laguna Harvey of the Linear Train Industries, the Corner family was able to manufacture the Gundam Thrones and the GN-Xs. Alejandro was also assisted by Innovade Ribbons Almark. Through researching Ribbons' genetic traits, Alejandro created his own group of Gundam Meisters, the Team Trinity. With pieces at his disposal, Alejandro Corner began his plan of destroying Celestial Being in A.D. 2307 to fulfill the Corner family's century-old dream.
Celestial Being, with their Gundams, declared war against conflict in A.D. 2307. Alejandro and Ribbons observed the situation and bid their time to strike their plan.
During Azadistan's economic, political and energy crisis, Alejandro Corner decided to choose the country for the United Nations to help build their Solar Energy Receptor Facility. Alejandro would later comment that he made the move to see the world move forward with his own eyes; he saw the country as one of those who had a chance to change for the better or plunge into destruction. At the height of political tensions between the conservatives and the reformist party of Azadistan, Alejandro ordered Ali and his men to attack the conservative party and kidnapped Massoud Rachmadi to incite war. The civil war in Azadistan was temporarily brought to an end by the return of Massoud Rachmadi to Azadistan through Gundam Exia's intervention with the help of Gundam Dynames. Behind the scenes, Alejandro and Ribbons observed Exia's actions as rather tool alike than god like.
During the Gundam Capture Operation in Taklamakan Desert, Alejandro Corner ordered co-conspirator Laguna Harvey to send out Team Trinity and save the Gundam Meisters. Alejandro later called the rest of Celestial Being Observers and convinced them to acknowledge Team Trinity as legitimate members of Celestial Being. Afterwards, Team Trinity carried out their attacks on multiple military establishments around the world. Their main purpose was to send the Three Blocs on the brink of military collapse. Due to the brutality of their operations and the civilian casualties they left in their wake, they also increased the world's resentment against Celestial Being.
Due to the nature of Team Trinity's armed interventions, the Ptolemaios' Gundam Meisters eventually decided to label Team Trinity as a source of conflict. Because of the possibility of Gundams destroying each other, Alejandro put forth his plan into the next stage. Somewhere in Antarctica, Laguna Harvey unveiled and distributed 30 GNX-603T GN-Xs to the Three Power Blocs. Because of their unified objective, they formed an alliance under the United Nations, the new United Nations Forces, to destroy Celestial Being. It was after the distribution of the GN-Xs that Alejandro decided to dispose of Laguna Harvey and the rest of the Observers, and Team Trinity through Ali al-Saachez.
While these events transpired, Alejandro, through Ribbons Almark, acquired the main terminal of Veda. During the UN Forces attack on CBS-70 Ptolemaios, Alejandro cut off Veda's support on the Gundams. However, Celestial Being tactician Sumeragi Lee Noriega had foreseen it and activated the Gundams' Stand-Alone Operating System. Upon seizing Veda's Level 7 data, Alejandro also acquired the cryogenic container of Aeolia Schenberg. While watching Team Trinity's demise, Alejandro shot and killed Aeolia in deep sleep. However, the action triggered a system trap which closed the Gundam Meisters' data from Veda and activated the Trans-Am System in the original GN Drives.
Due to the UN Forces' devastating loses in the Lagrange 1 against the Gundams, Alejandro eventually decided to assist the UN Forces by sortieing in his GNMA-XCVII Alvatore. Through Alvatore, Alejandro overwhelmed Celestial Being and was able to sink the CBS-70 Ptolemaios. However, he lost and died in battle against Gundam Meister Setsuna F. Seiei.
Nothing is known about the Corner Family after Alejandro's demise. However, some of his plans continued through Ribbons Almark, such as the construction of Memento Mori. After the A-Laws' demise in A.D. 2312, Alejandro became a symbol of the corrupted Earth Sphere Federation. In A.D. 2314, he was portrayed in the movie "Celestial Being" as the head leader of the A-Laws.
- Though not similar, the Corner Family's actions share what the Romefeller Foundation and Blue Cosmos/Logos did throughout the series as they manipulate world affairs by infiltrating the world government, sell weapons to cause war which leads to their true common goal: To rule over Earth.