Her beginings with X-Force wasn't exactly her own. When the team started up, The real Domino was being held hostage by Toliver, and her place was taken by "Copycat", a mutant shapeshifter and Toliver employee. Once the plot was uncovered, Domino had been rescued by Cable. Soon after that she officially joined the team at Cable's request. Due to her highly skilled battle tactics, and her talents with firearms, she became an asset on the battlefield.
Her past rarely ever came to interfere with the entire team, and when something did come up she handled it on her own. And everytime it does happen, it always seems to involve an old teammate from the "Six-pack". Whether its Grizzly becoming a serial killer due to the brain washing of Genisis, or Hammer becomeing paralyzed due to a botched mission with Cable, or Kane persueing a relationship with her bitter hated enemy Copycat. All these examples prove is that once she calls you a freind...she'll never let you down.
Domino took to Cable's side when the decision was made to split from the team. She then later parted ways with him and came back to X-Force. The return was difficult because she left them as children and returned to find that they have grown up. But even though their age had increased, thier maturety had not. Picking up the leadership reigns that Cable had dropped, Domino now fights alongside X-Force as no longer a teacher, but a trusted freind as well.