If it's one trend that tends to happen in Wittenberg-run games, it's that groups have a tendency to pick up NPCs. Games almost turn into harems, with hangers-on, henchmen, followers, and friends following the exploits of the PCs in any given game.
The Enigmatic Mr. Ebbs, I believe, first experienced this when he ran a Mutants and Masterminds game a few years back. In that game, the group gathered up NPC after NPC, with an angelic-origin PC nearly becoming pope! She had a full cult surrounding her, believing she was of divine origin and would bring about The Rapture!
This continued as EEE GMed us into the "Pyramid of Shadows"--one of the Wizards of the Coast-published 4e D&D modules. Trapped in the titular pyramid, our heroes began recruiting civilians and other humanoids who became entranced by the psionic call of the pyramid. It's from these humanoids--replete with randomly rolled stats--that we ended up with such luminaries such as Clevon Washington and The Goddamned Jim-Bob!
In fact, I even mandated the trend while running "Pirates of the Underdark", with each PC creating an NPC to serve above their ship, the Red Mourning. Details on all of those NPCs can be found in some of my earlier entries. The enigmatic wizard Durgrek, the mysterious investigator Nalen the Lesser, and Mathir's 'slave-boy' Elkantar all came from PotU.
And, so it goes with my weekly "Tear of Ioun" game. At first, it was merely one NPC. The players picked up Elladan Red-Hand, after he saved them from imprisonment during the Siege of Wellspring. His "Liberace meets Jack Sparrow meets Chairman Kaga, then becomes The Doctor" personality immediately endeared him to Lupin--the group's Banite battlemind/paladin--and Elladan's followed them ever since.
Following this, when we picked up a new player--Jess--she took on the role of Shantira, the lone Stormcrow that the group was able to save from the Forlorn Tower. A pyromaniacal eladrin warlock, Shantira's added ranged damage, numerous ritual castings, and a love interest for Lupin as the group entered the Shadowfell.
But were they done there? Oh, no. Rather, our runepriest--Russell--is out for his own kingdom! After his own clan was sundered, Russell received word from Thorgrim, his clan-brother, that a new delve was being founded back on the Prime Material plane, and needed his guidance! Russell, ever the pragmatic priest of Kelemvor, has decided to take it upon himself to lead his clan back to glory...
And what's best? I still have one great NPC in reserve. You see, Vaymeer (the Harrowfolk barbarian that started all of this mess) is still in the picture. Beaten twice, thrown into the Shadowfell by Lupin's githyanki blade, and marooned without his tribe, he's got an axe to grind with the party...and it's already sharpened and waiting.
Then again, one has to wonder...what happens when one sunders a githyanki silver blade? Lupin, Russell and company are about to find out! :D