Solo

Solo (ソロ) is the last descendant of the ancient tribe of Mu, as well as the human form of Rogue. He was orphaned as a child, and people often banded together to attack him during his life. His only friends had died to seal Le Mu/Ra Mu. As such, he is an extremely solitary person.

History
Solo says that people have always been afraid of him, and that they often ganged-up on him and rejected him as a freak. He can EM Wave Change because he draws his power from the lonely voids in people's hearts, essentially loneliness waves. He is hostile to Geo because he is afraid that Geo and his friends will come together to harm him (but they really have no intention of doing so).

Dr. Vega says that Solo is so obsessed with reviving Le Mu on his own that it goes to the point of him thinking of not working alone, while Hyde says that either way, he won't trust him. He denied Hollow's offer to use the Mu matter transporter, "Kamikakushi," saying his blood will not allow others to help him.

Near the end of the second game, Solo begins to have a change of heart. He saves the unconscious Geo from the falling continent of Mu, though when Geo speaks to him, Solo hides it with a response that "Your unconscious body was blocking my way out." This is a single, momentary and rather unhelpful change, as Solo later challenges Geo to a final showdown (as a secret boss, after you complete the game) to prove whether or not his power of loneliness is stronger than Geo's link power. He teleports Geo there sometime after the defeat of Le Mu (although it is unknown when, although it could have been a few seconds or a few months later, although the game skips straight to it after the credits), and asks him for a fight. (You can't save at this part of the game, but you do have the opportunity to walk around the surrounding area and rearrange your Battle Cards)

In the anime Ryuusei no Rockman Tribe, Solo works on his own, seeking the OOPArts to fulfill his duty of preventing the reappearance of the Mu continent. Eventually, he appears after Le Mu's summoning to hold off the deity from reaching Earth so that Megaman can destroy the portal that connects Mu and the rest of Earth, sealing Mu for good. Like Bass.EXE in Stream, he pulls a "dissappearing act".

In Megaman Star Force 3 he becomes an ally (though still only appearing as he wishes) and gains his own Wizard, Laplace. His design also changes slightly, mainly due to Laplace being able to change into the sword that Solo wielded in the previous game. He is less hostile than before, but tells Megaman that it doesn't change anything. Solo also accepts that there are many ways to become powerful besides loneliness, but Solo still decides to stick to loneliness with Laplace as an exception, continually challenging Geo throughout the game. He seems to walk in out of nowhere and disrupt whatever's going on, and once scared security so much that he was forced to fight some Police Wizards with the Laplace sword.