Long after Protea's death – Proteus had told her she couldn't walk on water; it didn't matter what it said in Sverige Alquist's big book on the subject – long after that, Proteus looked back with fond affection on their "first time". With fond affection, and of course a little embarrassment and a lot of consternation.
It just happened. They had already left the lab. Behind them, Proteus heard Alquist reading aloud. He couldn't make out the words through the closed door, but they sounded calm, impressive, measured. The next thing he knew he had Protea in his arms and they were kissing. What a ridiculous activity when you think about it! But at the time, he didn't think about it. On the contrary. What they were doing made all the sense in the world to him, emotionally. And then it was their "first time". Now, where did that come from?!
It was sudden, beautiful and strange, all at the same time. And a thousand other attributes could have been thrown simultaneously into the fire that consumed them...
Afterwards, they were fêted like heroes. They were the "future of Robotkind", the "saviours" of it. The trouble was Protea could deal with all the media attention; it was no skin off her nose. She just had to sit there nursing their son. (Their son! The first child born to a Robot couple ever!) No one expected anything more from her than that.
Proteus, on the other hand, was required to philosophise on the whole business, to make weighty statements on the significance of every single aspect of the “miracle”. In the end, he came to despise himself for his thanklessness. Try as he might though, he just couldn't get away from the fact that his life after the "first time" had been a complete and utter anti-climax. That in no way detracted from the fondness of his memory of the "first time" itself, but it did make him wonder if there wasn't more to life than just sex.