Witty, likes to make jokes, and enjoys learning new things. He is very protective of his friends.
He has excellent computing skills, and thinks much faster than any normal human, able to perform calculations and make battle plans in the blink of an eye. He can also be doing several things at once, and be in several places at once.
Leonard is one of the Smart AI, the extremely useful and quick thinking class of AI. However, they are few in number, as they are much more expensive than Dumb AI, which handle simple tasks like creating shipping lanes,and plotting slipspace routes. Leonard was “born” in the UNSC Sword Base on Reach, and, as is the case for UNSC AI, was told to pick a name and appearance. He chose the name Leonard, and decided to use the likeness of one of the ONI “spooks” in the room, a well dressed man in a suit and tie. From there, he was made the general assistant to an ONI facility on Luna, basically becoming a glorified file sorter. There he remained for six years, most of his life, without much to do besides snoop through the files being passed around the facility. Then he was reassigned to the SPARTAN-II program, put to the task of figuring out as much about the Covenant as possible. Dr. Halsey assumed the best way to learn about the Covenant, was to put Leonard with one of the Spartans, Mike-037. They served together for a few months before he spliced in along with Mike during the Fall of Reach.