Alright! Finally getting down to do this - Sorry, since I get time off with a PS3, when I'm not reading the Words of Radiance, I'm pretty useless!
Critique threads seem terrifyingly deserted these days! So are the writing groups anyway... Wonder if it'll pick back up at the end of the RPG, or if it's more dependent on the month and the stories?
@Henry Dale :
So, I voted for you, because I liked the dramatic slice of life. I really appreciated the fact that despite drama, despite risk, life just goes on, until drama strikes again.
I wasn't too fond of the ending, mostly because it was very abrupt, with no description of feeling at all. It felt cropped like you'd suddenly ran out of words and barely could squeeze that in. Two more sentences, or even just one, to sum up more about what it does to this little girl, or something similar, would have given me a better feeling of closure.
Incidentally, your cloud eaters called in my mind these drawings of demonic super monsters by Mike Mignola in BPRD :

What gripped me in your description of climbing :
Thu tied her length of rope with a carabiner to the safety harness that ran up along the long neck of her cloud eater.
What this brings to my mind is that she has a "sling" - a piece of webbing you have tied into your main harness loop at all time and use for anchoring yourself to hang in safety. Mine looks exactly like this but in Orange. Only one biner is truly necessary.

Some people use Daisy Chains, which are interesting for some purposes, but I do loath them :

What this quote also leads me to believe, is that the cloud eater has some sort of system embedded in him to support her climbing, like piercings of ring bolts? Or something similar.
Van bellowed irritated
I believe it'd be "bellowed, irritated". Might as well nitpick while I'm at it.

When the sun was out, she’d hang in the safety harness, legs dangling off the edge and basking in the warmth
This made me smile.

Did you know that spending 15min immobile in your harness will kill you? Which is why knowing how to do safety rescue, in case the leader or the belayer fall unconscious is crucial for people who do long multi-pitches?
Also, I can tell you, never mind my 150$ comfy modern harness with its wide supporting bands... there is nothing less agreeable than sitting in one a couple of minutes. It digs in your flesh, jams in your bones... It's not made to sit in.
Full body harnesses are a bit different. But yeah, sure, why not, you didn't say how long she'd be hanging in there...
Thu got up, tossed her bag of snow on the pile they'd sell next week when the merchant came and ran after Mai who was way ahead.
This is the one non-climbing thing that disturbed me really. How do you make a nice pile of snow for
a week, outside, without refrigerating? If it's cold enough in ground level, then why isn't there lots of snow there as well?
if snow is a precious commodity, they should sell it asap! Or else make her a cool room of some sort no?
It felt like you cut down words there, and it felt like a bit of a plot hole because of that :
What's the point of having a cloud eater? Isn't he their best possession? Why? From the cloud eating? Or because it's the only place you can get snow?
It's not explained, and felt like that needed fleshing up.
a dreaded scene however
Either a coma before however, or no however.
The climbing gear had to be here somewhere, she remembered dropping it when Mai tackled her earlier today.
No climber in their right mind would ever drop a harness and climbing gear on the floor where a cloud eater could trample it! Or the elements ruin it.
I guess you really have to take a terrifying, super exposed fall, or hang for dear life in a terrifying climb, for you to realise just how serious a situation you are in.
If the rope, or the carabiner, or the harness loop let go, you fall and you die. All of this can be averted by taking great care of your gear. Which includes : keeping out of the sun, out of sand and durt, and out of the rain, and particularly out of sea water and mist.
If she climbs every day, this girl becomes an instant dullard to me by treating her gear like this, and I lose a lot of empathy.
She found the bundle of rope in the mud but her carabiners and other hooks were nowhere to be seen in the dark storm.
At that point I'm like "omg, she deserves to die"
Muddy ropes? If she uses them for self belaying, going on in the rain with them is like committing suicide.
Also "carabiners and other hooks" make it sound like they're the same thing? They're not, it's different type of gear.
Besides, hooks are used for aid-climbing. If she did aid, she's lacking gear.
But we're still completely in the dark as to what she uses that for/on? Hooks to dig in his flesh? Hooks to clip a rope ladder on and sit back on her rope and progress aid-style?
Anyway, if you use aid climbing, chances are it's because you just can't physically do any free climbing at all - so how does she suddenly manage to free climb the beast with no tools in the wet??
And you just can't aid without a belayer or extensive gear for self belay! - addressed later -
She tossed the rope in a loop around the safety harness
What? Sorry what rope? Do you mean her anchor rope/sling/daisy chain? Because otherwise I have no clue what kind of rope she'd be using "in a loop" around her harness? Also, safety and harness are redundant, since you were a harness in order not to die.
Besides, if you did mean the same rope as the one she "sits" on at the begining, and I called an anchor sling, then it's never kept "in a loop around the harness".
For safety and pragmatical reasons. If it's a long piece of rope used to make a full anchor, then it'd be folded and carried like so :

If it's a small anchor sling to anchor yourself to a fixed point like the one I showed at the beginning, then you thread it through halfway into your harness main loop, called belay loop, it's in the middle here, in green :

then you clip both ends with a biner, twist it around to shorten it and clip the biner to one of your gear loop.
It's the orange twisted rope you can see along my hips here :

Don't mind the knitted Fantastic Mr Fox, I did it for a friend and took him up to have summit pictures shot.
If you really want her to carry her piece of rope in some easily imaginative fashion, then she'd carry it like this :

or
managed to balance herself and tie it around her waist.
This confuses me even further. One second she's on the ground "tossing" things around her waist, the next she's holding unto wet fur, struggling to tie the rope around her waist? There is a progress problem. She never left the floor at all so far as we know.
As to why on earth she'd be trying to tie the bloody rope around her hips, I'm still not sure at all. Refer to my previous points for the best way to carry a rope.
If she's using the rope to belay herself, then why does she uses a harness? That's what they're for.
Thu held on to the main rope and folded her feet around it at the bottom. Alternating between going up herself and moving her makeshift safety rope she climbed up on this familiar track.
Ha. The thick of things.
What main rope? Does she have a piece of rope that is fixed, X many hundreds of meters long, going all along the beast neck?
Also, what's your safety rope? the one she just tied around her waist for no reason while she has a harness?
If she fell unto that safety rope looped around her waist (instead of threaded through her apparently useless harness) she'd potentially hurt herself badly. That's why most makeshift harnesses include leg loops.
Like this :

ANYWAY. How the hell are you making her climb? It makes no sense at all.
Climbers need belayers. She can't be doing a self belay. This would require a ground anchor that would instantly break as soon as Van moves. Worse, after some 50m, it'd be pointless and require her to carry over 100m of rope on her back!
She'd also need a special type of Automatic belay device like a "silent partner".
https://www.petzl.com/en/Sport/General-principles-for-solo-climbing-with-a-fixed-belay-rope?ActivityName=Rock-climbing#.VpeU9vFXuRsSo, fine, she's not solo climbing by self belaying. So what do you mean?
That she is ascending the rope by relying on prusik or Klemheist knots?
If she is, then her using her feet on the rope is the worst idea. It'd be way more efficient for her to be with her feet on Van's side, unless the rope is dangling far away from him.
Now, using a rope to ascend another rope is a nightmare. People use ascenders, like these :

Seriously, if she's going more than 100m, sitting on prusiks, in the wet, while ascending a rope by grabbing it her feet is impossible.
She'd slip, jam the prusiks, be unable to disengage.
Prusiks would need to be moved while she's standing up, she can't be putting weight on them. It'd be horrendously strenuous.
Spoiler for Hiden:
Thu, Henry's hero, after a lifetime of climbing up Van :

lol sorry I can't resist taking the piss.
So yes, terrible ascension technique.
If she has biners, then she has metal, then she should at least have an ATC, and ideally an auto blocking one.
But in the end, if she's ascending, then she doesn't need a safety rope, she needs several cordelettes and biners, and ideally an ascender, a foot rope ladder and an atc....

she was dangling from her arms and a safety rope
If you refer to the same safety rope, then the use of "a" is confusing. Sounds like that rope just happened to be here.
She swung her legs forward and planted her feet into Van’s thick fur. It was slippery but at least it held her steady.
If she could do this all along, then she has minus one thousand reasons to be monkeying up the rope.
Worse, if falling actually pulls her against his neck, how does she manage to stay away from it otherwise?
She was in a safe position though, if she did slip she could abseil like this until she regained a secure position.

Have you abseiled before? Abseiling means going down the rope with some sort of belay device (atc, grigri, figure 8...) and maybe some prusicks.
If she falls, she doesn't want to abseil at all!
If she falls, she prays to all her gods that her nonsensical climbing system doesn't break her spine, doesn't slip on muddy/wet rope and land her on the floor (foreshadowing here...). If it held, then she hasn't moved at all, and she's just hanging there.
So as soon as she'd got her wits back she'd just keep climbing, not lower herself in order to climb back up.
Besides, story telling wise, you never establish that there are safety areas for her to rappel off of.
Worse, abseiling is THE most dangerous part of climbing. A large percentage of deaths occur during abseils. It's that and walking at the top of the cliff with no protection/rope, that kills most climbers.
There I just want to point at the fact that your main rope is also a terrifying concept. So far as we know it's a piece of several hundred meters long rope attached to the top and dangling to the bottom.
If anything happens to use or cut off that rope, how do you climb on your cloud eater? Pretty screwed.
Likewise, what are your safety ropes attached to?
If she's ascending the one and only rope, if that rope fails, the lack of redundancy kills her by dropping her as well. I'll address that in my solution.
Slowly she pulled herself up in the hope she’d reach the safe spot at Van’s head.
Tense and grammar problems here.
Her safety rope was wet and the knot didn’t hold
What? It's the Deus Ex Machina safety rope, wet and dangerous, that slips when she reaches the top for dramatic effect.
Now, also, you image of the rope not "holding" makes me imagine her falling down hundreds of meters of rope, while still attached to the "main rope".
That would leave her a lot of time to try and save herself, by any of the crippling and unpleasant ways one can stop such falls. She could lose a leg or burn her hands, but the way you describe this, she isn't in free fall.
Then again, I just re-read you. And you say "the knot didn't hold" - okay, if she is ascending, and using prusiks or
klemheist knots, then it cannot undo itself. It's impossible.

Mayyyyybe the double fisherman knot used to turn the cordelette in a loop could undo itself, but it is extremely unlikely, and nothing happens to risk breaking the knot or the cordelette, or the rope. She just slips! That's absolutely nothing. Carabiners, ropes and knots can withhold falls that, with factors, put hundreds of kilos on each piece. Slipping on the rope that is necessarily anchored/tied above her waist would weight it with almost less than her own weight.
So her fall has no reason to happen.
My solution : Now, a better system, in my opinion, that will save you time and more importantly make a very easy image in the mind of your readers, is to give them the idea that Van is set with a lot of rings.
Now imagine that Van is Xerxes' face, and that Thu put ropes (ideally chain) in between all these fancy rings on his right side, and boom, she can climb up his face.

More seriously, chain paths are common enough and allow you to stay safe while ascending or descending very steep scrambling that isn't yet hard enough to be a proper climb.
So, this system is great. I'd prefer chain, because it's more versatile, and she could use them to thread her fingers in as handholds as she pushes away against Val with her feet.
But rope is lighter, and you can imagine her usually climbing with a spare section of rope, in case one broke or frayed and she needs to replace it.
Such ropes would need to be often interrupted by Alpine knots :

That's another type f knot that cannot fail and unravel.
Here are my sketches :
http://imgur.com/KpL0R4B.jpgSo the idea would be that at all times she has two slings attached to her harness (which you mentioned but literally never used to climb), and a biner at the end of each. She'd have one attached to the rope at all times.
She'd climb with no other safety.
She would descend in the same manner, adding the idea that, if she carries a rope with her on her shoulders, she could use it to rappel, section after section.
But rappelling (aka abseiling) would not always be possible, since rappelling is going straight down (oh gravity!) while the chain/rope path along Van would not necessarily be all straight, and she'd need to be able to swing back to them.
Anyway, that hoping manner would allow her plenty of completely safe rests. She'd be able to sit in her harness with two slings attaching her to chains and shake her arms.
But these slings are precisely what would be her downfall :
We fall on
dynamic ropes in climbing. This is absolutely crucial, as using a
static rope could kill you.
That's why such drawings exist :

Here this guys falls straight on his sling (a daisy chain here), and of course there is no slack, he goes from falling to unmoving way too fast. It's like a mini car crash.
That's cause the sling held!!! In worst (and likely) case scenario, the sling simply snaps. They are meant to hold a lot of dead weight, but in a static manner, not a dynamic one.

See, in this drawing, the only thing holding this guy to the rock is his daisy chain. If he slips, the sling will suddenly become taut and stressed, and besides hurting him, will very probably just snap, sending him crashing to his death!
Best way to avoid that is to always shorten your daisy chain so it's taut already, or to also have the rope attached to you and to the anchor.
Thu has no rope, only slings, so it's dangerous enough, and the reason she keeps grueling around with two of them.
Arriving at the top, Van rears his head, and the slings, which are not meant to hold such dynamic stresses, snap.
Better, for tension, she'd still have one biner in her hand, not yet clipped.
Poof. Freefall.
I reckon that system makes more sense, implies no magic wet knots, no ropes to carry, minimal gear, and that saves you a lot of lines. No gear left in the mud like a criminal amateur, yet plenty of anxiety at the idea of climbing on wet fur and wet metal!
She'd also be able to rest, but would push on, fueled by stress. Also, a damn freefall would be quite the thing to depict, just the moment when she's snapped away from Van's neck, hanging in the air...
BUT, like I said, I liked your story. It was unpolished, and I wish you'd have asked me more about climbing to make it easier to understand and all... but if I'm the one who could best see your lack of sense, and yet voted for you, it has to count as a compliment... right?

I liked the world it seemed to depict, and I'd love for you to expend on it. Something with realistic climbing, and a sense of the economy and society, the community living with these creatures... Maybe from the later point of view of Mai, the poor kid, owner of Van, despite that the beast killed all her family, that'd be quite good.
Great work Henry!
P.S :
Just to validate my authority on the case(prove I'm not talking trash), and excuse myself for the harsh burn down of your world research, here's a video of myself, shaking my rack to a ukulele in a 2015 climbing trip. By the way, if you watch it in HD, you'll notice my orange sling tied from my belay loop to the side...
https://www.facebook.com/ele.nora.524/videos/1647508448809487/?l=4978767488353495264Also, anyone feeling like giving me a review of my story would be most welcome. No need to stretch it though... hehe.