When Kimrin was founded in 879, Poss' clan were among its settlers (Poss was 35 at the time, and his brother was 16). It has often been remarked how uncommon it is for there to be a 19-year age gap between siblings. Their age difference, however, is not the most commonly discussed aspect of the brothers' relationship; rather, it is the fact that their careers took such wildly divergent paths. Neither of them talks much about the other, though it is well known that there has long been bad blood between the two, owing not only to their having chosen opposite sides of the law, but also to the circumstances of their parents' death in 886. (For details, see Capp Primus.)
Poss and Capp's parents were hard workers, having long been employed as farmers on the plantation of one of Triscot's noble clans, before setting off for Kimrin to start their own farm. While Kimrin never became nearly as affluent as Triscot, and none of its citizens as rich as many of Triscot's, their farm was among the more profitable ones in Kimrin. Poss himself had been in the Triscot police department since the age of 25, and helped organize the Kimrin PD, when the village was founded. However, he didn't accept a position on the force for the first few years, opting instead to help his family get their farm up and running smoothly. Once it was clear that he was no longer needed, he joined the PD in 882, and by 885 had become its chief, upon the old chief's retirement. It was only a year later that his parents died; some have said that their funeral was the last time Poss ever saw his younger brother in person (prior to 912), though this is of course mere speculation.
It is said that Poss was one of the key figures involved in forging the Northern Alliance in 897, when officials of Kimrin and Port were approached by The Order and informed of The Plan, which at the time was virtually unheard of in any other villages of the Land. He also was instrumental in forming the army of Kimrin, and became General of the Army in 901, and is considered one of the most important people in the Coming of the Order. However, it was roughly two years earlier that street gangs around the Land's various villages were beginning to step up their criminal activities, and branching out into other villages, forming alliances with other gangs. Little is known about how all this came about, but one of the two most prominent gangs on the Land, LandOrder, is now known to have been cofounded by four gangsters who came to be referred to as "dons" (meaning the head of a village's gang), one of whom was Poss' brother, Capp. At the time gang activity was increasing in 899, Capp was 36 years old, and had been head of the largest gang in Kimrin for about thirteen years. By the time the Coming began, Poss and Capp had had little if any contact with each other since their parents' death. (It's well known that Poss privately blamed Capp for their death, though the police ruled it an accident.) When LandOrder was officially formed by uniting at least four villages' gangs (more would follow in the years to come), Capp became its capo (meaning head of an inter-village gang). People have sometimes wondered if Poss could be trusted in a position of such power in the military, having such a major criminal in his family. However, the bad blood between them is well known, as has been mentioned, and so little stock is put in that association by most people, especially those close to Poss.
In 904, after the passing of the surname law, Poss and Capp both took the name Primus. The name means "first," and for Poss it refers to being the head of the army (and later the entire military). It's unknown if he and his brother had any discussion about the name at the time, or whether one chose it first and the other later chose it after hearing his brother had assumed the name.
In 905, the newly elected king Demos Royal promoted General Primus to Marshal, a new position which put him in direct command of all branches of the Military. At that time he officially moved to First Village, though he spends much of his time at Army HQ in Near Port and Navy HQ in Port, as well as occasionally returning to Kimrin, to visit old friends, check in on the family farm (co-ownership of which was bequeathed to Poss, Capp, and the farm's employees, upon the death of the original owners), and also to check in on old comrades in the police department. Of course, when in Kimrin he also usually makes an official visit to the local regiment, which until the latter part of 912 was under the command of Colonel Stavros Supprus. Poss stays in his family's house when he's in Kimrin, though it is now occupied by the family of the farm foreman, Jerald 'Jerry' Inheritor (whose son Bruce replaced him as foreman when he retired in 908). It is believed Capp hasn't been to his family's farm since his parents' death.
It should be noted that in spite of their differences, Poss and Capp Primus have much in common. For one thing, they are both tall, powerfully built, dark-haired men, with rugged features. Many people find their stature imposing. They are both quite dedicated to the people under their command, but also demand excellence and integrity from those subordinates (even if many people would question the intrinsic integrity of those who work for Capp). Both are greatly respected by those they command. They are both of a serious disposition, especially since their parents' death, but both also are capable of relaxing and enjoying themselves, when "off duty." Both are intelligent and strong-willed, and both have a tendency to exercise caution, but are willing and able to make bold moves when necessary. They both have relatively few friends, but have a deep appreciation for and strong bond with those friends.
It should further be noted that in 912, they each individually forged an unexpected alliance with The Chaos, which ultimately renewed contact between the brothers, to some degree. Of course, they're still on opposite sides of the law, and so their relationship remains somewhat distant. For Poss's part, this alliance came somewhat later than it did for Capp. It was a result of Demos Royal refusing to abdicate the throne after losing that year's election to Quinn Darkstrider. While most of the Kimrin regiment under Col. Supprus's command changed loyalty, joining the Chaos, other regiments sided with Demos. This left Poss with a smaller power base with which to defend the right of the newly elected king to assume the throne, which necessitated his alliance with the Chaos against Demos, during the Chaos War.