Yunho made it back home in the evening and worked through a placement test Wooyoung handed him for his classes so they could estimate his knowledge so far (not that he had any) when the peeping sounds on the door told him someone was trying to come in. Just as he pushed back from the table, the door swung open and a man shouldered inside. He had a sports bag over a broad shoulder and cradled a box in his hands, trying to close the door simultaneously.

When Yunho appeared in the doorway, he was met with a dimpled grin.

"Hey there. Could you help me for a second?" He held out the box and Yunho grabbed it so he could come in. With a huff, his visitor kicked off his shoes and placed his bag on the floor.

He wore his black hair short and a healthy tan warmed the hue of his skin. His slanted eyes formed into crescents from the might of his grin. Over all, he looked like a very polite cat.

"Choi San, your new roommate. Sorry about the mess when you arrived. Wooyoung chewed my ear off," he winced, but Yunho shook his hand with a friendly grin.

"No worries, you had no idea I would show up. I'm Yunho."

Relieved Yunho wasn't stuck up despite his nerdy glasses, San beamed back at him.

"Born 99, right? We are the same age."

"Hell yeah," Yunho grinned before he moved aside so San could come in. He placed the mystery box on his table while San shrugged out of his varsity jacket. He was ripped, the shoulder to waist ratio meticulous, hard work. Though he was a good bit smaller than Yunho, he could probably throw his weight.

How lucky he seemed as nice as Wooyoung promised.

"I brought you cake as your little welcome party. I hope you like it, otherwise I can order some food for us," San explained with a nod at the box. When Yunho whirled around like a possessed man, San stifled a snicker in the cosy sweater he shrugged on to wear at home. A gym nut, through and through, but he looked like an even politer cat now.

Once he unwrapped the spoons that came with the cute chocolate cake, Yunho got them something to drink. He was already comfortable around San. Perched on the ground with each other, San was just as casual to greet him.

"Wooyoung told me about you and your struggle with Auresce. So sorry to hear what you had to go through. Hoping it only gets better from here on out." They toasted with spoonfuls of cake and Yunho tried the treat. Very sweet, so he would eat from it for several days, but it was delicious.

San also seemed satisfied.

"I'm glad Tenebra found me. It's a better experience already."

"Glad to hear it. Always ask me as well if you have esper-related troubles. We can also train together. Well, muscles. Our powers aren't very compatible."

Yunho sucked on his spoon and blinked at San through his fringe and his glasses.

"Wooyoung called you the S-rank esper most famed in Tenebra. What can you do?"

Though he looked smug at the compliment, his explanation was pretty wise.

"I can dissolve myself and the things around me into acid. Like bleach, think bleach."

Intrigued, Yunho thought back to what Auresce preferred. Acid sounded like a risk both to San and to his surroundings. Especially with such a high rank. Was he one of those people they shunned and tried to get rid of?

"The upside is that I can deal with pretty much all demons by dousing them until they are nothing but spots on the ground. The downside is that all of my bodily fluids are acidic, so I'm to be touched with caution."

Yunho nodded. Acidic bodily fluids definitely meant that San would have frequent organ issues. He probably ate himself from the inside whenever he used his powers.

But he looked at peace with the looming dread of an early death. Since he used his powers for something good, there was a purpose in his pain. 

Perhaps he could teach Yunho to be less scared of his gift. Hiding away didn't get him anywhere. But if he could live genuinely like San, he might find his peace as well.

San shovelled cake into his mouth while he explained. Aside from Lux, Yunho hadn't talked with an esper of such high rank and he was fascinated how remarkable their abilities could be.

"Most abilities have an opposing power somewhere that would work against them. In my case, it's all chemical. Alkaline substances kick my butt, so if you mostly see me eat weird things... Please understand," San snickered, and Yunho nodded eagerly.

"Totally. You eat whatever you want."

Merry with the piece of cake stuck in the corner of his lips, San continued.

"We have a couple of people like that and though they might look shady, you don't have to be afraid. We have fewer guide losses than Auresce, despite being labelled oh so dangerous."

This time, Yunho dared to ask. If Wooyoung heard of it, everyone else also would, but his curiosity was never quenched.

"What about Mingi?"

"Mingi? He's the best guide in the country." Confident, San preened in pride at their leader. Some would argue guides weren't as suitable commanders since espers were always stronger, but not in Yunho's opinion. Without Mingi, he would be dead. No matter if he was an esper.

"Not just in Tenebra?" He made sure, but San insisted.

"Definitely the country. He often flies out because he is needed for high-class esper guiding overseas. He is an S-rank, and he has good compatibility with a lot of people."

That made Yunho hesitate. So he had no single pair. Though guides could work with anyone, perfect pairs were always worth the effort to find. If he was so good, he surely had some people he matched with pretty well?

Yunho hated the immediate judgement that washed over him. It meant Mingi did a lot of things with a lot of people. Yunho wasn't special.

Even now, knowing guiding had its purpose, Yunho couldn't help his upbringing. The thought of using sex so casually repulsed him.

Better to ask San about it than a guide, though. Yunho played with a loose thread on his pants, not looking at him as he mumbled into his collar.

"Guiding... Isn't it a bit... Embarrassing?"

San peered at him with the spoon between his lips. Looking adorably innocent, not like someone who dissolved living beings into acid.

"No, why?" Unperturbed, San caught up on his half of the cake, not minding how Yunho barely ate anymore because he would suffer a sugar shock otherwise. Since the cake would just land in their mini fridge otherwise, Yunho let him.

"People kiss on a battlefield... Or do worse." He described, hoping he wouldn't sound too prudish. The publicity of things was a hangup for Yunho, but that was his personal preference for intimacy. Much more bothersome were the implications of guides becoming objects of sexual gratification because their powers supplied fast rest and recovery. Like Lux, people would abuse that opportunity. Like an addiction, only that people with thoughts and feelings were attached to it.

It was difficult to explain, since everyone seemed absolutely nonchalant about this part of their world. Yunho always found it odd.

San shrugged it off.

"What better timing for a kiss of life? I wish I could kiss my Wooyoung there."

Yunho pricked his ears. 'His' Wooyoung?

"Wooyoung is your guide?" Yunho guessed, but San's lip jutted into a pout. Only another spoonful of cake could appease him. He looked like he kept telling himself this bite was the last only to dive back in once more.

"I wish. Wooyoung is an A-level guide, which is below my class. He works hard to become my partner, but... My time is limited and he can improve his abilities only slowly, so it's a risk to team us up when we aren't equal. We catch every moment we can get."

Though a grim reminder, San didn't lose his cool. Yunho looked down at his socks, sorry to hear that. They sounded close, more affectionate than just an esper and a guide. No wonder Wooyoung was so comfortable talking about him.

"But back to your question. Have you received guiding before, Yunho?"

The abrupt blush on his ears had San chortle at him. His smile turned smug, no different from other cheeky guy friends Yunho hung out with. At the end of the day, even if he could turn into acid, San was also just a person.

"Oh, it must have been good if you are that flustered."

"That's not it," Yunho muttered, hiding his face as he pretended to adjust his glasses. San made some crude gesture and wagged his brows at Yunho, only tormenting him further.

But he liked Wooyoung, right? As a person? Despite not being a pair?

"I refused so far and got in trouble for it. I never went further than touches with my guide back at Auresce because anything else felt inappropriate. Ah, and Mingi helped me out that one time. That was the first time I received proper-ish guiding."

San's eyes hadn't been this big before.

"Mingi did? Oh boy. You will be the talk of Tenebra if that gets out." He played down his shock, but Yunho's head tilted.

"I thought he was open about being a guide? He just touched me politely. There was nothing racey going on."

Though Yunho got a look that told him not to lie, San's proof was the squirming and fidgeting of his new roommate. No one was banging Yunho when he jumped away like a scared cat at the mere mention of guiding.

But if San told him it was better for Mingi's reputation as the official CEO of Tenebra not to be reduced to a guide, Yunho would watch his mouth.

San finally put down the spoon and sprawled out. Yunho didn't mind his faint smell of sweat, but he should remind San to shower before they went to bed.

"Everybody wants a piece of him. Begging at his knees, basically. Fuck, the few times Mingi guided me were like heaven on earth. Since his guiding is so notorious, only a lucky few ever get it. To think an outsider was quicker than some who have been trying to get with him for years. Serves them right. And I'm not surprised. Mingi likes cute things."

"Cute, what-" Yunho choked on his spit, doubling over with his cough. San laughed at him, but was kind enough to hand him some water to chug.

Once he wasn't dying anymore, Yunho sank into himself, mortified. Mingi was top-notch, huh? Yunho could barely remember what he did, only how good it felt. Washing all pain away, even some he never knew he had.

San looked giddy about his new information. He would definitely tell Wooyoung, so Yunho should pray not all of Tenebra would hear.

"He's famous for it, after all. But don't get used to it. He helps here and there, but his main concern are S-ranks, of course."

"Of course," Yunho parroted in a mutter. Not that he could ever ask anyone for guiding, much less his new boss.

When San shut the cake box, Yunho moved along and collected their spoons.

"Concerning guiding, you will have to get used to it. Treat your guide as a person, then you won't have a guilt issue about using them for sexual favours. They are ready to help, otherwise they wouldn't offer themselves. Without them, espers are nothing, so strictly speaking, we are at the palms of their hands."

Somehow, that made sense. Yunho would be dead without Mingi and he was quite sure Tenebra was only running because of Wooyoung's passion for these people.

"Practise in private until then. Few of us love to do it on the battlefield, but it's a last resort when we are close to losing ourselves or badly hurt. Since you soak up damage, you will probably need a lot of guiding."

"What if I want to save myself for marriage?" Yunho asked, while San placed the cake in the fridge. 

A coo answered him.

"Good luck with that. In that case, we won't take responsibility for your untimely death, though. We help, but you need to accept guiding. So ease into it. There are great people out there."

San patted Yunho's shoulder to return to life as regular roommates outside of work topics, but Yunho's back was tense as he threw away the spoons. 

He couldn't get used to that thought.