He takes that invitation and lets his tongue dive into that opening. Exploring and tasting the inside of the Xingchen's mouth. Curling around the other tongue as his hands start to work on the ties holding the man's clothing in place.

Xue Yang has waited a long time for this and he feels no need to hesitate any longer. He intends to drink in this entire moment and make it last but first it requires being able to see and appreciate that slim body that is hidden beneath those robes.

He doesn't know how Xingchen wants to do this but the blindfold means the man probably intends to let him be the one in charge of this. Xue Yang isn't afraid to take or receive in these kinds of things. Both have their advantages. But i this instance the desire is definitely to take, wanting to be the one that steals away that purity.