When Caine was back in boot camp he’d heard a version of that line a million times, to keep his attitude and willful instincts in check. He was faster, better, and stronger then all the humans entering the Legion and it irked him that he had to act like he was less than he really was around them. The drill sergeants practically had to beat it into his head because he knew it wasn’t true. He’s just enhanced. But the instructors lumped him in with all splices, as if splices were only worth something if they were obedient soldiers. The experiences carried with him, even though he hated hearing it every single time it was barked at him by his drill instructors.
So, Caine was used to pushing people away with that line. It was usually enough to get people to back off or find out if they were only after him for some animalistic thrill. He knew the latter wasn’t what Jupiter was after. But he didn’t want to fall for her, only to have her toy with him and then dump him - when a splice lover wasn’t convenient anymore. That happens to splices all too often.
It wasn’t that he didn’t want to kiss her then. It was damned hard not to… taking so much of his will to step away from her. He had troubles even controlling his voice as he told her that she shouldn’t involve herself with a splice. But when that line came to mind, he presented his resigned poker face and just spit it out like every time before - to bomb the conversation.
What he didn’t expect, was her genuine acceptance with that ridiculous line about always loving dogs. That line - it was so awkward - for BOTH of them! It threw him for a complete loop - leaving him gaping and blinking for a second before he could make a quick exit. But when he left and heard her berate herself for the line, he couldn’t stop himself from looking back and giving the briefest of smiles - he knew what she meant by it.