Alright...so....I was wrong. By Datu's consistent pain at viewing and understanding of a 'command' not 'translation' I was off on the theory that it was phillipino tribal stuff. Whoops. Let's see, where to start? I've been out of the foil hat game for a few months (and theorizing in general) so let me dust off the hat and give it a shot again.

A lot of popular things in the thread, just want to say I second them. Scratch probably got into the Colony and heard the cry for help from Tanya, that can't be good. I mean, Burt keeps laying his fears about giving locations away over radio, even if its secured, doesnt that plant the seed of doubt for us in the landline? And a perfect point for Burt to bust in, in a few episodes to save them with Riley and blast Scratch away with a hilarious 'told you so'?

To that point, hell, what's to say Ink doesn't know what's going on? He always seems to? Maybe he's watching the colony, and tails Scratch to Cain, and we have an epic battle royale? Scratch attempting to take the baby due to some crazy "I-wanna-be-a-mom" thing inside of her, as Ink busts in and is like "A HYBRID BABY! PERFECT FOR TESTING!" (Saul's immunity/elevated levels, and Lizzy's presumable normalness). All this and Burt's silently listening to the radio for something like this to go down. And to TOP IT ALL OFF, we got crazy Entwalker-Behemoth walking around all tree-barked out. It practically writes itself, no?

Or maybe Ink just shows up and tells them to give him the baby and no one else gets hurt. He goes all Rumpelstiltskin on us? (Yeah, I looked it up, that's spelled right dammit

Alright, the tunnels...Big stretches here, but we know the zeds dont like the haze...we know the haze is coming from the cracks...Maybe they banded together to dig some tunnels to re-route the haze away from where they want/need to be? Or, Ink banded these things together to reDIRECT the haze to wherever he desires. Letting him conduct tests as he sees fit. Try a few different drugs, give 'em the haze, how'd they react? Maybe Ink really is still trying to solve the 'how do we overcome this plague?', That's far-fetched, but c'mon, supreme multiple-disorder anti-hero. Part of him wants to eat us, part of him wants to save us from the outbreak! This doesnt quite explain the zeds going INTO the tunnel, since they avoid the haze, but c'mon, i'm trying here.

Now, since I was wrong about Datu having previously knowledge of this "Language", and I still maintain Kc's grounding by some science, I want to try and figure out these 'commands' via symbols. I've got two sketchy theories.

1 - The virus unlocks something in our brains, some sensory perceptions being heightened. We've seen that the zeds smell better, generally, what's to say they dont SEE better (or differently). Cats see infrared, we cannot. We all accept the rapid muscle development, why not some rods/cones development. The symbols aren't as much about what WE see (some lines/colors) but what the Zeds see, perhaps some crazy vibrant light structure existing in wavelengths outside our perception. There's light going on all around us that we can't see, what's to say these aren't written in some form that Datu can now percieve? Not sure how this links to him feeling commanded/in the backseat, but it was the first thing that came to mind when the language theory was debunked.

2 - I have to go back to listen to when Datu was attacked, but he was left alive. That seemed odd at the time, but we kind of just glossed over it when he seemed within inches of death. That means the little ones that attacked left him at least breathing, no? Well, we've heard Little Ones speak, perhaps they're capable of hypnosis, as taught by Ink. Hypnosis would explain his compulsion to follow seemingly meaningless triggers. He sees one thing STOP. He sees another COME IN. He takes a backseat in his mind and cannot stop himself. This theory lacks in the idea that ALL of the zeds would have to be hypnotized at some point, or at least Ink's army. Perhaps in the video of Ink being busted out of the van he took that moment and hypnotized the Zeds, which is why the listened? This is out there, but throw in some drugs Ink could've perfected that affect someone's susceptibiltiy to suggestion (As previously mentioned by Witch_Doctor, forgot the plant/drug, just that he mentioned it started with d-a-t-u). If he gets the virus to effect the subject suggestion, it could be some form of hypnosis. Which would be why they dont 'translate' they just 'command'. MOREOVER, Ink planned Datu's attack, and wanted him to bring Michael to the church. This was all a set up....