Dream didn't bother to prep him, like Wilbur did. Just kept muttering about how lovely a wife Techno would be once they'd done this, how good he was going to feel, how Wilbur should be grateful he didn't kill him on the spot.
Techno's head lolled to one side, as Dream started to push in.
The heat still coursing his veins, still keeping his dick hard and aching, seemed to soothe the pain a little, make it glide easier inside. Stopped him from trying to squirm away, dulled all the horrible feelings of 'I don't like this' and 'please don't touch my dick'.
Wilbur's eyes were glistening, void-deep as Techno stared into them, trying to give him a reassuring smile and ending with more of a grimace. They didn't break eye contact once, as Dream thrust, panting and moaning louder than Wilbur ever had, the grip on Techno's hips bruising.
OR
Continuation of the cult au, Dream decides its Techno's turn to enjoy the full experience of being an adult, and leads him off into the forest. Wilbur comes chasing after, fails a rescue attempt, gets beaten to shit, is forced to watch, and then gets his dick sucked with broken ribs.