Abandoned by his parents in a junkyard and later picked up in an orpahange, Pat suffered from that event and thus he developed a split personality disorder. One being the good guy (Pat) and the bad guy (Rey). And for unknown reasons, he met with the FM-ian Gemini and is enrolled in Echo Elementary School.
Pat meets with Geo in the middle of MegaMan Star Force at school, and Geo gets a good impression on Pat, saying that he's a nice guy. Eventually, the two began to talk more and Pat revealed his origins to Geo. That was the last nail on the coffin, and Geo asked Pat if they could be Brothers (via Brotherband). Pat wanted to, but Rey (evil side) didn't want that. Finally, Rey relented and things seemed to be alright. However, right when the Brother band was formed, Rey emerged and EM Wave-Changed with Gemini, and caused havoc in the shopping district by creating positive and negative waves that caused people to bicker. However, they were soon stopped by MegaMan, who destroyed the Rey version of Gemini (there are two versions, one white and black, Pat and Rey respectively). After the battle, Rey became dormant in Pat, but the damage was done. Geo and Pat exchanged a few words, and both went their separate ways uneasily. Geo returns to his paranoid, pessimistic self and Pat was nowhere to be found.
Pat would return, however, when Gemini Thunder (max form of Gemini without Pat's help) was about to attack MegaMan. Pat came between both combatants and took the shot from Gemini. Things were ultimately settled there, and Pat would help to bring Geo back to Earth when MegaMan went off to space and fought the FM King and Andromeda.
Sprigs would appear in Star Force 2, but he isn't found in Star Force 3.
Personality: Pat and Rey were more opposite than plus or minus. Pat is incredibly soft, nice and almost seems to be calm, no matter what (even in the tense moment after the fight with Gemini. Rey, on the other hand, is ruthless, cruel and is bent to serve only Lord Gemini.