[he can see and feel every jerk and twitch and reaction, hear every soft noise of effort and ragged breath he wrings out of Lan Wangji as he tries to keep steady under the assault...

eventually he snaps and slams them forward until Wei Wuxian's back hits the other end of the tub, shoving deep into him at the same time, teeth bared and eyes narrow golden slits, as feral-looking as Wei Wuxian's ever seen him]