The Pack is the name Nathan gave to the mercenary group he founded after fleeing Mistra. Though the surviving members have since left the mercenary life and accepted Nathan's offer of employment with Elpis, they remain a group of highly competent - and dangerous - people with a wide range of skills and contacts.
For Nathan, before there was the Pack, there was another pack - his fellow Mistra operatives. Some of his old friends died on Youra, while others went on to join up with his second pack and later, Elpis, where they have finally found a way to live productive, happy lives.
In the years prior to coming to the mansion, Nathan fought off more than one retrieval team sent by Mistra to bring him back so that he could be reconditioned. On one occasion, he fought Morgan one-on-one, incapacitating him but refusing to kill him because of their past relationship.
The events at Columbia University brought to light some troubling trends in the nature of Mistra's operatives. Instead of the highly stable and disciplined first-generation operatives, the Spartans, Mistra was now putting former criminals and mental patients into the field with second-generation conditioning. When he was recaptured by Mistra and reconditioned, Nathan discovered that his former friends and even some of the more stable operatives who hadn't known him were desperate to have him back. Nathan's guilt over having left them grew after he was saved by the X-Men, and even rescuing Mick Foley and shutting down two conditioning centers didn't help matters.
The events in Canada and the retrieval of Morgan were a more significant victory. The Mistra operatives were now leaderless and Mistra itself was crippled. Unbeknownst to the X-Men, the other members of Morgan's team from Canada had also been affected by the Trojan Horse. When the X-Men and the US government raided Youra, Morgan's team helped them. Though a number of them were killed or critically injured, their assistance was critical to the success of the operation.
The survivors were given counseling by the government, but several of them soon decided that average lives in the US were not for them and left to join the Pack in Africa, assisting in shutting down training camps where young mutants were being shaped for lives much like what they themselves had so recently escaped. After Bridge's death and the fall of the house of Morrow, they all took up Nathan's job offer and joined Elpis, working out of the Tel Aviv office.
Several of them were seriously injured when the Preservers bombed the Tel Aviv office. All are on the road to recovery, however, and the incident has only strengthened their bond with their colleagues and friends, the former members of the Pack, and their determination to continue living their new lives.