Actually, my character Eldran is no longer a tribesman, he's the son of a minor noble from Furyondy

(The first draft of the background is at the RG thread).
Regarding connections, if Red Knight's elf hails from the Highfolk, it would then make sense that he and Eldran fought together against Iuz's forces in the Vesve forest. Both during the war hiatus (between the end of the 'Greyhawk Wars' in 583CY and the Furyondian Northern Crusade' in 586CY), and in the years since the wars, Eldran (and possibly RK's elf) has traveled extensively throughout the mid-Flanaess, around the Nyr Dyv, the Urnst states, Dyvers and Greyhawk, and as far south as Celene abd the Ulek states. In his role as a knight of the Hart he may have traveled as far as Tenh! (King Belvor and his Knights can ill afford to ignore the Devil-seeing Ivid of Aerdy, who still sees Furyondy as a rebellious province).
His motivations are not mercenary but... as a pragmatist, he would certainly have welcomed Yurei's aid, and perhaps hired him for some 'jobs' hunting the agents of Iuz, the Scarlet Brotherhood, or other enemies.
RKs character woud likely have many of the same motivations, and could have contacts in Celene (maybe it was on Highfolk business they traveled there?)
Anyways, I name a couple of crucial battles in my background: the fall of Crockport, northenmost province of Furyondy. The siege of Chendl, its capital. And later on, the retaking of the lost northern provinces. Any of the others who are from the central Flanaess could have been involved --as mercenaries, citizens, or merely passers-by -- in any of those events, and we could have met.
As it has been several years since the war, I am open to suggestion in terms of more recent connections.