Unbeknownst to Clark, when a Kryptonian meets their ideal mate, their teeth will elongate into fangs and they have the insatiable urge to bite and claim. Clark and Bruce are working together on a mission when Clark feels a heat course through him and an ache in his canines, all while he's near Bruce. When they get back to the Bat Cave Bruce notices how quiet Clark is being. When he comes closer, Clark snaps. He overwhelms Bruce and sinks his now elongated teeth into Bruce's neck, claiming him and also making Bruce feel pleasure the likes of which he has never felt before.

Things escalate from there, with Clark and Bruce both claiming each other thoroughly. It's when sense returns that the epic freak outs begin, along with the chance of actually being together.