Solo

Solo is the human form of Rogue. He says that people were afraid of him, and so they often ganged up on him and rejected him as a freak. He can Wave Change because he draws his power from the lonely voids in people's hearts, essentially loneliness waves. Why he's so cold toward others is because he's the last living person from Mu. He's also cold to Geo because he's afraid his friends and him might gang up on him and hurt him. Basically, Solo is the last of his kind. 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. Hyde says that either way, he won't trust him. His blood led him to deny Hollow's offer of using the Mu matter transporter, "Kamikakushi," saying his blood won't allow help.

Then soon near the end of the game he starts to have a change-of-heart at the end of Megaman Star Force 2 he saves Geo though he hides his kind feelings by saying "Your body was just in the way so I moved it here." He still does not hold too much respect towards Geo, due to the fact that Geo relies on his friends, eventually challenging him to a final showdown (as a secret boss) to show whether his power of loneliness or Geo's Link Power was better.

In Ryuusei no Rockman Tribe, Solo works on his own accord, seeking the OOPArts so as to fulfill his duty of preventing the reappearance of the Mu continent. Eventually, he appears after Le Mu's summoning to hold off Le Mu from reaching Earth so that Megaman can destroy the portal that connects Mu and the rest of Earth, sealing off Mu for good.

In Megaman Star Force 3 he becomes an ally (though still only appearing as he wishes) and gains a Wizard Laplace. His design also changes slightly, mainly due to Laplace being able to change into the sword he wields in the aforementioned game. He is somewhat nicer than last time but he tells Megaman that it doesn't change anything.

Trivia

 * Even as he becomes nicer to Geo, Solo's powers strangley remain the same, unlike the fact that he has gotten less lonely and that should have affected his powers.