The tunnel was a bit tight for Casey to crawl through, but he could tell that it was no natural formation. Some expert digging creature was responsible for them, and as such there was care given to make sure the tunnels wouldn't easily collapse. Hopefully. Maybe. Casey gulped suddenly as his doubts started to creep in.
But the call of the unknown was loud. It felt almost palpable. Like a taste on his tongue, or a lick of flame on his face, or a magnet in his heart. Either way, Casey felt more like he had to go inside, find the end of the tunnel.
And then his nose caught a whiff of ... something. Fruity. But it seemed as sweet as rotten peaches. Just a smidgen of the scent. Not anything he was used to, but it still felt that the source was deeper in. And he had to find it.
The moment he brought his hand down to move forward, and it met only air, Casey suddenly was not sure if he was going to find the source. This thought hit him just before slipping off a ledge, tumbling down the slope and into a chamber within the cave, where he'd lay in a daze for an unknown amount of time.

Some scittering noises brought Casey back to consciousness. The young roo put his hand to his forehead, and slowly sat up, nursing his aching temples. He opened his eyes and did his best to adjust to the dim light within the cave, recalling where he was and what his surroundings were.
As his perception slowly returned, Casey started asking more and more questions. Specifically, how could he see around him? What light source was there in here, that he could see anything? Why didn't he bring a flashlight to explore this place? Why was his hand sticky?
Casey paused again, and looked down. He was sitting on something dark and sticky, something that looked hard yet oily and slick. The sensation on his hands felt immediately familiar. It was the same as that waxy resin he had seen in the tunnel in the abandoned worksite just the day before.
Casey's heartbeat raised as he felt too heavy to get up. And again when a ghostly outline of something caught his peripheral vision. As he whipped his head around to inspect the ghost, his eyes caught a wispy glimmer of light. It was no ghost, it was some sort of thin veil. Held together by what looked like stretched taffy. With some sort of thin film between taffy strings.
Casey's heart stopped. He recognized the look of webbing immediately, and wished to be literally anywhere else but here.
Especially since he suddenly felt something was watching him. From somewhere behind him. And he didn't want to turn around to find out what. But, with strong protest, Casey found himself unable to resist turning around anyway.

What immediately triggered in Casey's mind was, well it was not an arachnid. Or at least, it didn't look like one. He's seen crime dramas and action films where spiders and scorpions were featured prominently and clearly, and what stood behind him didn't look enough like them. There was a carapace and a sizable abdomen behind it, but no spindly legs, no oversized mandibles and pap-hands. No multiple black eyes. But more than four limbs.
Casey felt the air was stale in here, as he panted heavily. His fur bristled where it was neither matted by the resin nor dirtied by the mud clods. The back of his neck was itching from nervousness. "S-stay back... I'm... sorry for... intruding... Just, had to see what was here... You're supposed to have a permit to do anything in here, 'c-cause the city owns this lot, yeah? Y-yeah..."
A rather sturdy feminine voice responded from the dark. "How did you find this place?"
Casey paused. His heart was trying to escape his chest through his esophagus, and he struggled to gulp it down so he could respond, slowly raising a hand pointing off towards the tunnel leading the way he had come. "I... I saw... two of your... tunnel entrances..."
The shape in the shadows spoke mostly to itself. "Curses... So the air holes are not small enough to be covert. I must dig more air channels."
The creature then turned back to Casey, and stepped closer. The roo could make out a few more features on its face, such as the large hands and feet, their claws gleaming in the dark. And two masses of bouncy flesh on its chest.
"Oh... whoa. Y-you're... n-not gonna eat me..? Please?" Casey's voice was on the edge of tears.
"You may be more helpful to me than that."
The young marsupial held his breath.
"I know your kind depends on sight more than other senses. Come further in, there is more light down below."
The creature walked past Casey and crawled further into one of the cave paths. Casey hesitated, looking down one path, then another, then another, before looking back up the pathway he took to get here... and decided to follow the host.

Casey slipped through a small rock outcropping, wriggling his hips in order to find the right angle to slip in, before finding himself in a space where he could finally stand up straight and tall.
The cave walls were astonishing. A pale green and blue glow lined the walls, following the contours and shapes of the resin that encased the chamber and made things feel warm and a little bit humid, instead of the cold and damp feeling a cave would usually have. Some water dripped down from holes in the ceiling into pools. What looked like portals led to other tunnels and, Casey felt, a system of chambers like rooms in a house. Or like a roughly-organized ant colony.
In the blueish-green glow, Casey was finally able to get a good look of the one hosting him. From this view, as the creature scooped up some water in its three-fingered hand and brought it to its mouth, Casey could see the curved horns attached to its helmet-like head crest. Three spikes ascended on its forehead in a row. The upper set of shoulders and its wrists were covered in darker, segmented armor; its two feet were covered in darker armor that protected its claws like boots. Behind its back were a set of four insectoid wings, folded up as they were currently unneeded. 
Then there were the two massive breasts on its chest; they hung uncovered, nipples and areola darker than the rest of its skin. And between the legs, Casey could see that this creature was featureless. No pussy, no dick, nothing there. Just smooth muscle curving back towards the abdomen.
As Casey followed this specimen, he caught another glimpse at this creature's anatomy. The abdomen that stuck out from its butt like a tail was bulbous but stiff, not able to bend or sway like his own tail. It looked like it was ridged, similarly to an accordion, and looked like it could expand and contract as needed. It was an ovipositor, an egg-laying limb. And at the far end of it, Casey could get an eyeful of the ringed opening that served as the entrance, and exit, to the uterus. And oh, he could see the moisture and excitement inside.
"Holy shit..."
Casey's mind raced as he took everything in. And something clicked in his memory. The memory of something he remembered hearing about. Something from years back, something that showed up on the news for a bit. Something a bunch of scientists talked about in the news, before a bunch of those reports and documentaries and interviews suddenly disappeared. But Casey remembered them.
All except their names. What were their names..?
"You must return to your domicile soon, correct?" The creature kept its distance, but not so far away to keep out of Casey's immediate line of sight. And it certainly was not in the least bit ashamed about its nude appearance before Casey. "The sun has fallen a few minutes ago."
"... Oh! Uh, y-yeah, yes. My parents are... Flippin' hell, you've carved all this out here... You better hope nobody else around here calls the city."
"I will need to redouble my efforts to cover all of those entrances, then. I will need to make more so that there's still breathable air in here."
"Y-yeah, it's... a bit stuffy in here."
The creature paused slightly. "The air here is of efficient comfort levels. ... For my kind. It is too warm for you?"
"Uh, a bit. And a tad too humid. It's, like, one or the other. ... You were at the construction site, weren't you?"
She blinked. "I admit, I followed you when I could. I have to hide."
"Wha... Why me? Why follow me?" Casey suddenly got nervous. If this had to be kept secret, what would happen to him now that he knew about it..?
"You ... intrigue me. And, I reiterate, you may be more helpful to me otherwise."
Casey's eyes were unable to decide whether to focus on the creature's amber eyes, or on her breasts. It seemed that she didn't mind, however. The sight of hefty female titties was enough to keep some sort of mental block in his mind. Unable to remember what that damn name was...
"Hah, h-helpful... how?"
"I require someone that can teach me. Something my Evisceroid instincts won't."
Casey heard a sound akin to a glass falling onto the floor in the dining room. Not the same tone, but duller. And while that sound echoed in his mind, slowly a realization hit him.
Evisceroid, she had said.
Those... alien bugs. Alien bugs that breed in the thousands per hive.
The documentaries about their anatomy, their social structure, the amount of damage they could cause, the sites of some hives being discovered and exterminated. The carnage.
Casey's breathing became very thin and rapid, and his heart rate increased. He felt the sweat drip down his face. Panic was setting in.
"Evis...cer...oid. Oh fffff..."
The creature lifted her head and looked over him clearly, reading his fear like a book. "You have heard of my kind."
Casey slowly took a step backward, then another, before finding himself against the wall. Unable to escape. Need to escape.
The Evisceroid did not move forward to pursue the young roo. "... Evidently so."
"I... I know what you do..." Casey could only whisper, but his voice echoed fairly well inside the cavern. "You're a... hivebreeder? You find some guys... males... and you use them to make, like, millions of eggs. Growing a hive... infest... attack."
She looked down at the cavern floor, but otherwise held her ground. "I am indeed a hivebrooder. Orphaned, as it were, from her home."
Casey was still afraid for his life. He knew what Evisceroid hivebrooders would do. It was something that he and Robbie would talk about occasionally. Of course the thylacine looked at the prospect from a kinky angle, thinking it would be awesome to have a strong ovipositor attached to his malehood, sucking him off strongly multiple times a day. Casey, however, was horrified by the rest of what the documentaries said. That the males wouldn't survive such treatment for very long.
But the usage of the word 'orphaned' made him hesitate. Long enough, it seemed, for the hivebrooder to continue.
"You are exhibiting a fight-or-flight response. Which means you are threatened by my presence. Likely a result of what you have heard about hivebrooders such as myself. Or Evisceroids in general? Hear me words, as I too have learned... of what danger I can pose."