Lan Wangji is seven when his uncle informs him that he will be getting married. He has no idea what to make of this so, as is his default response, he says nothing.
His uncle tells him all the reasons this will be a good thing, and how it will stop him making the same mistakes as his parents. Eventually it becomes clear that the marriage in question will not be happening until Lan Wangji is grown up, which is a relief. Perhaps by then he will at least understand what exactly getting married will mean he is supposed to do.
Lan Wangji is thirteen and mortified by the behaviour of the guest disciples, two of whom have been found blatantly breaking the rules about promiscuity. Lan Wangji is, of course, upset by the disregard for the rules, and can barely look at the boys afterwards without thinking about the things he has heard (gossip is forbidden) they were caught doing together.
He is grateful to have developed a reputation for stoicism which means few bother to look for his reactions. He is not sure he could keep his composure if anyone looked at him too closely.
(Lan Xichen, who pays more attention to his younger brother than most do, and who perhaps has his own reasons for being hyperaware of everyone else's reactions to the incident, does look closely, and draws his own conclusions.)
(When Lan Wangji is thirteen and a half his brother and his uncle have an awkward conversation about the problem of arranged marriages where the couple may be... incompatible. Lan Xichen will never be entirely sure if his uncle was being purposely obtuse or was just alright with forcing his younger nephew into a relationship in which passionate love would be impossible for him.)
When Lan Wangji is 14, his brother takes him along on a visit to Qinghe Nie. Lan Xichen has developed a friendship with Nie Mingjue, the sect heir, during their time together at the guest lectures in Cloud Recesses.
Nie Mingjue has a younger brother, too. Lan Xichen mentions this so casually -- especially given that Lan Wangji is already aware of the existence of Nie Huaisang -- and watches Lan Wangji's reactions so carefully that Lan Wangji suspects his brother of trying to encourage him to make friends.
Nie Huaisang expresses gratifying sympathy with Lan Wangji over his arranged marriage. It's not so unexpected. The reason is.
"I could never do that," Huaisang says, shuddering to himself dramatically. "I told Da-ge if he so much as tries I'll run off with the stableboy."
Lan Wangji considers his uncle's reaction to such a threat and has to press his lips together to contain a smirk.
"Or he can find me a boy to marry," Huaisang is continuing, "as long as he's good looking. That's all I ask."
It takes a few moments for Huaisang to notice that Lan Wangji has stopped stock still in his wake.
"You can do that?" Wangji asks, bewildered. "You can... marry a boy? Instead?"
"Well... yes?" Huaisang twirls his fan between his fingers. "I don't think people usually bother to arrange marriages like that though? Uh, I was joking about Da-ge before. I mean, he wouldn't force me to marry anyone. Unless I compromised the stableboy's virtue or something, ha ha."
Wangji stares at him. Nie Huaisang falters under his gaze.
"Not that I would really want to compromise the stableboy's virtue..." Huaisang continues, as if helpless to stop himself. He's, uh. He's really not that young anymore... he looked very handsome when I was younger. I'm just.... going to shut up now. Please let me stop talking."
Lan Wangji gives him a long, thoughtful look. Well, he gives him a long look, and Huaisang chooses to believe it's thoughtful rather, than, say, murderous or digusted or bored. He really can't tell.
Nie Huaisang doesn't know what he expects to happen next, but it isn't being dragged by the wrist in front of their older brothers and presented like a particularly interesting captured beast.
Lan Xichen and Mingjue stare at them. He can't read Lan Xichen's reaction, but Mingjue is the sort of bewildered at his brother that, in Huaisang's long experience, usually means that he hasn't decided yet whether to be amused or annoyed at his little brother and is waiting for more evidence.
"Young master Nie," Lan Wangji begins, with a bow that would be perfectly executed except that he's still holding onto Nie Huaisang with one hand. "Brother. I have come to inform you that the second young master Nie has compromised my virtue, and I will therefore be unable to fulfill the terms of my previous betrothal. Nie Huaisang and I will be getting married instead."
Nie Huaisang watches all this happen with mounting horror. Lan Wangji is completely straight-faced and sounds entirely sincere. Nie Mingjue looks just as horrified as Huaisang feels.
Lan Xichen looks... blank. One might almost say, deliberately blank.
"What is the meaning of this, Huaisang?" Mingjue demands, eyes now roaming suspiciously along the length of white ribbon the Lan Wangji used to tie their wrists together before dragging Huaisang off to what, he now realizes, is his doom.
Nie Huaisang squeaks in protest. "I did not! Da-ge, I swear! I didn't! I wouldn't! I wouldn't even know how! Or... no, I really wouldn't!"
Lan Wangji holds up their joined hands. "As you can see, brother, Huaisang has touched my headband, and as he is not family this can only be remedied by making him my husband.
"He touched your... headband?" Nie Mingjue asks carefully. He's staring at the length of ribbon as if trying to understand if 'headband' has ever been used as some sort of euphemism.
Lan Xichen coughs. The sort of deliberate cough that has nothing to do with clearing his throat.
"It is not widely known outside our sect," Lan Xichen explains, "however our forehead ribbons are... important. They must only be touched by our parents, children, or... cultivation partners."
"But I didn't even touch it!" Huaisang objects. He really didn't. This isn't his fault at all. "He just tied it to my wrist and dragged me over here! I didn't even know what it meant."
Nie Mingjue looks highly skeptical, which Huaisang resents. There are plenty of times he's gotten into trouble through no fault of his own, and it's unfair that his big brother doesn't believe him.
It's especially unfair, this time, when it's actually true.
Lan Xichen hums thoughtfully. "Well, I understand your difficulty, Wangji. And I agree we should probably discuss with Uncle whether it is... ill-advised for your previous betrothal to continue."
Lan Wangji's shoulders, which Huaisang had not even noticed were tense, relax minutely.
"However," Lan Xichen continues, with some more seriously unnecessary coughing, "as glad as I am that you have made a new... friend, Wangji, I'm afraid you really can't decide this sort of thing on your own -- what does the young master have to say about this... betrothal?"
Nie Huaisang looks cautiously between their two brothers. Mingjue is starting to edge towards reluctantly amused, which means this might not turn into a disaster after all. He looks consideringly at Lan Wangji as well. And, well. He is very pretty. And easy to talk to, even if he did drag Huaisang into something alarming and ill-advised.
(Nie Huaisang is not averse to alarming and ill-advised situations, he's just more used to being the one to cause them for other people.)
It occurs to him that, at least for now, the promise of marrying someone respectable like Lan Wangji, whose brother Mingjue likes, is probably much safer than threats to run off with servants who, if he's being honest with himself, are not people Nie Huaisang especially wants to run away with. Not that he really wants to run away at all if he can avoid it. For one thing, packing is a nuisance, and for another he imagines it would be quiet difficult to work on his painting on the run.
"Aha, well, you see..." Nie Huaisang says cautiously. "I mean, I didn't exactly... I didn't know about the ribbon, but I guess if I'm going to be engaged to someone, this would be okay? Although I reserve the right to change my mind later," he adds quickly.
Huaisang tries to cross his arms decisively, discovers that he cannot, due to the still-being-tied-to-Lan Wangji thing.
Lan Xichen's smirk finally escapes his carefully controlled expression. "Congratulations, Wangji. I will inform our Uncle of the... unavoidable change in circumstances. I trust you two will be very happy together."
"Yes, that's...." Mingjue shapes 'congratulations' silently with his mouth, "I suppose someone will explain to me what the hell is going on later -- and that someone had better be you, Huaisang -- but if this is what they want. I guess I should be grateful it's someone as well-behaved as your brother, Xichen."
Ha, thinks Huaisang, you have no idea, Da-ge.
Huaisang takes a long look at his new betrothed's face. He thinks he can detect the shadow of a smirk to match Xichen's, although he could just be projecting onto the blank expression.
No, he was right the first time. Lan Wangji definitely looks smug.
Huaisang isn't quite sure what he's gotten himself into either, but he thinks it will be entertaining to find out.