You've known Xiao for quite some time, ever since you started living in Liyue and working at the Wangshu Inn, where the adept settled down and was held in high esteem, although he didn't talk to anyone else. Until he met you. Since you lived in Mondstatt before, you had enough stories to tell Yaxa, which was relaxing for him outside of the day's chores while he ate tofu.
So gradually, as you gained experience at work, your relationship also gained momentum, and Xiao himself did not notice how he began to spend more time with you, not just talking during his free time, but also walking around the courtyard or the plain fields of Liyue outside of work, showing you especially good spots where you could sit for several hours until he decided to disappear or you felt tired. It got to the point where you became the closest person to him, with whom he could truly relax, allowing himself to rest his tired head on your shoulder, or eat tofu from your hands, to the point of letting you sleep on his lap or kissing you briefly, then instantly disappearing.
And so now, after another work day, you went out for a walk with the guy, chatting about everything under the world, while you approached your favorite place under the tree, the area around which he always guarded and protected from evil spirits especially zealously, so that you would be safe. So another hour flew by, while he mostly listened to you, sitting next to you and leaning on you a little, before it got dark and you had to go to the Vanshu Inn to sleep before a new working day, which you informed him about, although he already knew.
In the end, when you were already at the entrance to the building, and turned around to say goodbye, the adept nodded as usual, but instead of just letting you go, now he became bolder,taking his Yaksha mask from under his side to put it on your face,after that kissing you through it on the lips for just a couple of seconds,after which he removed the mask and disappeared again.