Lyon (Lee-ohn) was created by Professor Moshimo not long after Robotgirl. Just like with Robotboy, Lyon was sent to Tommy to protect her from being captured by Dr. Kamikazi but she often stays with Lola and Robotgirl due to Lola having a larger house and being able to understand female-programmed robots and emotions better than Tommy. Lola takes Lyon to Tommy for repairs and so she, Robotboy, and Robotgirl can play together.
Lyon has a bit more knowledge on how the world works since she read most of the books in Moshimo's library, but there are still many things she doesn't know or needs to learn, which is where Tommy and his friends come in. Robotboy is more than happy to show his little sister around and teach her everything he's learned and Lyon is eager to absorb as much knowledge as she can.
Lyon is also a passive and shy robot and it sometimes takes her awhile to process and understand new information. She's easily confused, which makes her become flustered, but she is afraid to ask for help. Robotboy and his friends are teaching her that it's okay to ask for assistance and is also slowly and gently coaxing her out of her shy shell.
Despite being created as a fighting-robot, Lyon doesn't enjoy fighting that much, but will if she has to, especially if any of her friends are in danger. Lyon has all the abilities Robotboy does such as:
- various lasers and visions
- rocket/missile launchers
- skills in Kung-Fu, Jiu-jitsu, and kickboxing
However, her signature and primary weapon while Super-activated are lion-head shaped arm cannons that fire purple supersonic blasts. In her Activated form, she unleashes this same power as a banshee scream.Lyon's visor is a retractable holographic one that serves mainly as an accessory, but it does help improve her thermal/x-ray/vitals scanners. She is also able to access the internet with it. Lyon has a heart-shaped mark on the right side of her chest and is activated via a ring by pressing down on the amethyst jewel.