Targen was a freelance bounty hunter, not prone to taking sides in the Galactic Civil War. Well, not until he collected an Imperial bounty on a Twi'lek named Sarin'ek, that is.
Sarin'ek - Sarin for short - was a smuggler working covertly for the Rebellion and had run afoul of an ISB agent, thus earning the 15,000 credit bounty on his lekku'd head. A short space battle between the two ended in Targen incapacitating Sarin's YT-2400 in orbit around Abregado- Rae.
While en route to the prescribed drop off point, Targen made the mistake of engaging Sarin in conversation. The very persuasive Twi'lek knew a bit about Xextos and played off that to convince Targen that abandoning his current line of work to fly for the Rebellion would be even more exciting and dangerous than tracking down living beings for profit.
Sarin was right and Targen couldn't be happier with his decision. The pay sucks, but surge of adrenaline he gets from flying into battle can't be bought.