Born to Kelvin and Hope Stelar, Geo shares his father's interest in space and the stars. However, when Kelvin vanished during his job on a space station, he was devastated. He became introversive and mostly sad. His mother, Hope, thankfully let Geo out of school, which was the right thing to do, because Geo admitted that he could've done something that he would regret. Because of him not wanting to go to school, he was often tailed and taunted by Luna Platz, class president of Geo's class, and her friends, Bud Bison and Zach Temple.
Geo's life turned to a drastic direction when Omega-Xis (or Mega) arrived to Earth and he collided with Geo in Vista Point, Echo Ridge, which enabled his Visualizer (glasses that his father wore) to see the Wave World clearly. And after a debacle with Mega, Geo relented into working with Omega-Xis and he turned to Megaman whenever he would fuse with Mega, in return for information about Geo's father, which Mega claims to know.
Since then, nothing was ever the same. From introvert to unwilling hero, Geo goes out and now blasts the living crap out of viruses and evil FM-ians. During his adventures, he met with Sonia Strumm, who was in the same position as Geo (she lost her mom) and after spending time together, and a fight in the Wave World (in which Sonia turns to Lyra Note with the help of FM-ian Lyra), they became good friends and she joins Geo in his hero duties. In fact, Sonia once asked Geo to go shopping with her (Lyra's idea)! He also met with Pegasus, Leo and Dragon, three AM-ians (beings from Planet AM, destroyed by FM-ians and Planet FM) who would give Geo the Star Force, an advanced ability that would help him to combat future problems (mainly, the FM-ian invasion and its mean-machine, Andromeda)
Later on, Geo met with a student named Patrick (Pat) Sprigs and they also became good friends. But when they wanted to form a Brother-Band, Pat's ugly secrets were revealed. He has a split personality disorder (with the eviler side being Rey) and he works for Gemini, one of the better henchmen of the FM King. It took a battle to knock back Pat back to his normal self. But after that, Geo became his old, sad, introvert self again. It took persuasion from Pegasus, Leo and Dragon for him to return to his duties as a hero and to stop the FM King and Andromeda. To do that, they needed to go to the space station where Geo's father was last seen.
It was there that Geo learnt of his father's fate. He was captured by Planet FM and they were tried and they were about to be executed. However, Mega was then guarding his cell, and he let Kelvin and his crew mates go because Mega was also planning revenge (for his destroyed home in AM). To do so, he turned Kelvin and co. to electromagnetic waves so they can return home, and Kelvin was stranded in the depths of space ever since.
Megaman beats Andromeda, but they spared the FM King, as a gesture to him that friendship (and love) prevails. The FM King was grateful and is willing to spread the word to his people. Geo tries returning home, and despite difficulties due to the collapse of the station, does so by getting into the capsule, and being guided back to Earth thanks to his friends with their Brother-Bands (when the navagational system of capsule is broken).
Personailty: The quiet kid of Echo Ridge has come a long way. In the beginning, Geo is anti-social due to his dad's supposed death and he didn't go to school because of that. But after being with Mega and later Sonia, he became more open and brave. However, he easily gets knocked when people close to him stab him in the back or when they die, especially when its a big thing (eg. Pat's betrayal, Father's disappearance). We'll see how he adjusts later on in future games...