This is a random idea that I'm not very confident about but I thought I'd post it in case it spawns some better notions: do you think the horde that arrived at the Hospital could be the group that attacked the Mallers in the park ambush? I'm thinking the bodies they have in tow are the slaves the mallers left behind.
The only thing that makes me think this is wrong is that there are Behemoths with this horde and I have't heard Bert mention any little ones. So I'm thinking this isn't that group. But bear with me while I toss out a random little story line: Ink/Pin Stripes has been using the hospital as a base of operations, along with a handful of other Smart Ones. Slowly Ink has been amassing an army, a group that is seperate from the horde at the Arena. With the destruction of the arena, Ink was able to recruit a great number of refugees from there. The result being the great horde that now returns to the hospital. To thin?