This was first discovered during the battle of Paradise High School at the moment where Bernie Kosar fights with a Piken and tells John to escape. John later uses this legacy to swap thoughts and feelings with another Piken and persuade it to help him against the Mogadorians, which it does. This Legacy allows Four to share a bond with his Chimæra.
John also uses this legacy at the zoo, on his date with Sarah, when he gets the lion to roar and the monkeys to high five Sarah.
As this Legacy is one that Number Four (the most recent incarnation of Pittacus Lore) developed without the use of Ximic, it is assumed that all those who have had the title of Pittacus Lore naturally have this Legacy.