Yeah, I know that's one hell of a long blog title, but it's spot on the money.
Back in the day (1970's... how's that for additional parallelism with D&D-based gaming?), Marvel introduced Marvel Team-Up as a vehicle for their most popular character at the time, Spider-Man, to introduce new characters to the comics audience, or perhaps characters whose titles weren't doing too terribly well and even, occasionally, stars of other media (issue #74, as recently plastered all ove G+, included the Not Ready For Prime Time Players, the guys starring in the first season of Saturday Night Live). The first volume of the MTU series ran from 1972 to 1985 (when it became Web of Spider-Man, one of my favs as a kid), was revived in volume two from 1997-1998 and again for volume three in 2005 through, I believe, 2007 (I can't find a firm date on the end of the series). This last volume was written Robert Kirkman -- the writer behind The Walking Dead and Invincible (sorry comics fans, I know there are non-fans here on the blog, so I've gotta do a little Day One, Lesson One stuff here, too) -- as one of his first forays into Marvel Comics. It's this version of Marvel Team-Up that I think really does a lot to inform how I want to run FLAILSNAILS games in Ur-Hadad.
The basic formula of Kirkman's MTU works like this: hero meets problem, hero meets another hero (or heroes) also tracking down that problem, the heroes engage the problem in a manner that requires both heroes to (go figure) team up, and either (a) defeat the problem or (b) beat it back enough that the next group of heroes have to deal with it. At the end of each comic (except the longer, multi-book arcs), the plot is more or less wrapped up, but is embedded with leads to the next issue's story and conflict. All in all, Kirkman's model follows a great path to involve as many different sorts of characters in diverse situations, facing down villains that those heroes normally would never end up facing down on their own, just like 1st level FLAILSNAILS characters joining a group of 5th-6th level characters in their quest to kill a dragon.
It seems to me that a similar formula would work well for a more narrative-based FLAILSNAILS game (like that I'm more likely to run in the city of Ur-Hadad; sure there might be site-based stuff, too, but the primary motivator is the narrative). Adventurer A (or group of adventurers A) is introduced to a problem and begins to investigate. As they do, they meet up with Adventurer B (or group B), and possibly have some sort initial tussle (this shouldn't happen every time, but enough that it's a thing) before teaming up to face down their common foe. At the end of the session, a detail or series of details are introduced as a direct precursor of or breadcrumb trail that leads to the next bit of adventure. The goal of that bit of logic is less to give a clue as to what I'll be doing next as it is to provide the players with a hook so that they, as players, are more interested in showing up next time. For example, at the end of the first FAILSNAILS In Ur-Hadad scenario, A Night In the Lucrewarren, it was revealed that the thugs who killed off the vermen bore sigils of the terrorist/revolutionary group called the Bloody Successors. This detail led the players to ask a bunch of questions about the Bloody Successors and even to contemplate risking the reward offered to them by the merchant from whom illegal gods were stolen (the price of the reward was their silence) and report the the terrorists to the Captain of the Lotus Gate. So now, the players, knowing full well that the Bloody Successors are out there doing something nefarious, but needing evidence as to what it is, have a reason to show up to the next session, A Night In The Spiral Market. Any characters who show up to this session who weren't there for A Night In the Lucrewarren will be group A, introduced to the plot from the get-go, hooking up with group B (the guys from last time), since group A will need more concrete reasons to partake in the adventure.
All in all, the structure provided by Mr. Kirkman allows for a quick and easy integration of disparate characters and groups of characters into a simple conflict and story form. Yeah, it ain't great writin', it ain't terribly innovative, but it is a great tool for moving into the story as quickly as possible and planting the seeds for the next story, hopefully just enough to get the players interested enough in what's going on to come back to see what's going to happen next.