Kaeya did not usually interact with the bio-alchemist, preferring their status quo of non-interference. But needs must and so here he was, knocking on the laboratory door.
He knocked his knuckles on the door, with the other hand counting three seconds before on the other side of the door was heard a gasp, tinkling of broken glass and a cough that gradually grew louder as the assistant to the Head Alchemist moved towards the door. It was soon open and there in the entrance stood Sucrose, every part of her clothes, face, and hands covered in dark glittering soot. In her hands, she held a towel with which she had obviously tried to wipe the powder as evidenced by the smudges on the cloth and the patches of partially cleaned skin.
"Hello Sucrose," Kaeya greeted the green-haired scientist as he took her form in. He then glanced over her head at the visible part of the laboratory and held a wince. Whoever was going to clean it was going to have one heck of a time. The soot seemed to cover every single horizontal and vertical surface available. The Hilichurl's skeleton Sucrose had at one corner of her laboratory was though suspiciously clean.
"Sir Kaeya," the woman quietly greeted him back with a small bow. "H-how do you do?"
"None of that 'Sir' business, please," he waved off the title, as was the tradition when he was dealing with Sucrose. "I am marvelous, but if we may drop the politeness requirements and get to the reason why I am here…"
"Oh, o-of course," the towel in Sucrose's hands was slowly turning glittery black from the way she was fidgeting with it in her hands.
"Did you, by any chance, recently spend a day with Klee?"
Sucrose furrowed her brows, the towel now becoming a ball.
"I, I was the designated babysitter," she confirmed, eyes not even looking at the Captain.
"Was it, by any chance after one of your research sprees?" Kaeya already knew the answer, but he had to hear it from her.
"Uh, ma-maybe?" At least now her hands were completely clean. The same could not be said about the towel.
Kaeya raised his right hand to massage the bridge of his nose.
"Well, we've got a situation that requires your input to solve it."
Kaeya held in one hand the heavy bag Sucrose had packed before they both left the laboratory, while the other pointed out the new landmarks.
"Here the goose-fish had initiated their invasion," Kaeya pointed out the burnt remnants of the hilichurls camp.
"I a-am sorry?" Sucrose stopped dead. "What?"
"Goose-fish," Kaeya repeated. "The scout that reported this was not very imaginative and he named them as he saw them. I also didn't believe him until he showed me a photo of the animal in question."
Sucrose at this extended her hand, requesting the picture to see for herself. Kaeya fished the picture out of a pocket and passed it to the scientist.
On the picture was indeed depicted an animal that could be called a goose-fish. It had goose feet; the body was that of a fish that gradually elongated into the gooseneck which carried a fish head. It also held a tip of an arrow in its mouth and was charging the photographer. Behind it, other specimens were depicted advancing on a group of Hilichurls with bats and shields. Some of the members of said group though were running out of the frame.
"What? How?" Sucrose spluttered as she continued to study the photo.
"Well, in my case I would need to know the answer to the question of how to get rid of them, although the answers to your questions also sound very interesting." If only to be able to prevent this situation from happening.
The pair followed the trails of destruction and broken Hilichurl weaponry, with Sucrose stopping from time to time to try and gather material like fish scales or feathers to study the Goose-fish specimen later at her lab. Soon they came to an edge of a cliff where they took a small breather.
Kaeya was standing guard as Sucrose started a few tests to see to which of her chemicals will the new species be sensitive. She put some of her scales in tubes of acids and poisons when a loud cluck was heard. Both the humans were startled (although in Sucrose's case Kaeya was not so sure) and immediately went into action with Sucrose quickly storing the tubes in the bag Captain Kaeya had graciously brought out for her. Kaeya himself took a position in front of the bio-alchemist.
"Sucrose, we might have to run for it," he quietly told the female crouched behind him. She glanced around his feet to see a gaggle of geese-fish being joined by a plump descending from a cliff above them.
"Ugh, Captain Kaeya, we might not have that option," Sucrose pointed out the edge to which they were so close.
Kaeya raised his head as if whispering a small prayer to whatever Archon could and would accept before materializing his sword.
"Would you mind releasing some of your Forbidden Creation?"
"Not at all," Sucrose took a small vial out of the bag before uncorking it. "On the count of three!"
"One!" The gaggle was fully grounded and all of them had a weapon clutched in their snouts.
"Two!" Kaeya pulled out a small bottle of water also uncorking it.
"Three!" "Anemo Hypostasis Emulation!" They cried out simultaneously as a honk was heard all over the gaggle as if a war cry calling to take up arms and attack the humans.
A Large Wind Spirit erupted from where Sucrose threw her vial and a moment later it was infused with Hydro from the bottle Kaeya threw a split second after Sucrose. A lot of the geese-fish were immediately pulled into the center of it and with Kaeya unleashing his elemental skill all these animals were frozen solid. A few hurls up in the air and they vanished in puffs of smoke.
"Sucrose, again!" Kaeya shouted over his shoulder as he unleashed his skill once more before having to parry a goose-fish that had managed to acquire from somewhere a small sword.
Sucrose threw two more vials from which the Large Wind Spirits also erupted, each pulling a large group of the precisely named animals with Kaeya flinging some of his water inside to infuse them again.
Those three bursts had managed to decimate a huge part of the gaggle but there were still a lot and the pair was slowly pressed closer to the edge of the cliff.
"Sucrose, we might need a repeat performance of your burst!" Kaeya was physically fighting these geese-fish, trying to push them back to allow for some breathing room but with the height difference, it was an uphill battle.
"Uh, you are all out of the water though?" Sucrose asked as she dug inside the bag. Kaeya winced a bit at the not-accusation. "It doesn't matter. I think I have an idea I would like to try."
The small tinkling of the glass bottles as she mixed a new concoction was covered by the relentless honking of the geese-fish. As soon as it was ready, she announced as such, and Kaeya quickly moved to the side to allow the bio-alchemist a clear view.
"Forbidden Isomer 23 - Crepuscular burnet!"
Sucrose threw another vial that quickly exploded releasing a Large Wind Spirit. Kaeya frowned as he watched the new Spirit take form, change its colors into a darker green with red spots and promptly finish off the rest of the geese-fish, leaving behind a few of the specimens which immediately tried to leave the scene of mass culling.
"Keep one of them alive!" was heard before Kaeya threw himself at the remaining quickly disposing of and capturing one of them with an Omni-Ubiquity Net that the Traveler gave him before.
When Kaeya got back Sucrose had already packed her bag and was jumping from leg to leg, her hands extended towards the trussed animal and a quiet chant of 'Gimme! Gimme! Gimme!' could be heard from the bio-alchemist.
"Here you go," Kaeya gingerly presented the struggling animal to the woman and picked up the bag ready to escort the scientist back to the city of Mondstadt.
Later this evening, when Kaeya was organizing the schedule of Klee babysitting he swore to never again put Sucrose on the schedule without making sure she was not coming off a research spree.
AN:
Crepuscular Burnet, also known as Zygaena carniolica, is a butterfly that can be found in most of Europe. They are also toxic for their foes. Apparently, it has HCN (hydrogen cyanide) in all stages of its life.