In episode 21, Zero Two asks Dr. FRANXX if he had brought her to plantation 13 to see Hiro again. He replies with, "who knows, its not like I was expected you two to rekindle what you had." But, I think this is not the case. He had that lab partner that helped create the anti-ageing thingy, and I think he would do anything to see that girl again. Correct me if I am wrong but I am pretty sure she is his deceased wife. So anyways, I think he did this second hand, by getting Zero Two and Hiro back together! Even though he says didn't believe that they would get back together I think that I can confidently say that was the whole entire purpose of bringing her there. It's true, that he couldn't make a promise it would happen, but it's was the reason. So, did he know? I say yes! He wanted it to happen while at the same time he couldn't ensure it would work. I would say him saying "who knows" is just a way of him showing that he wanted it but didn't know if he could have it. It could also show that he did it without realizing what he was doing himself. He may have simply been searching for code 016 for a reason he wasn't sure of until he saw Zero Two's connection with him. Then, he realized! But, whatever the case, I believe that he knew- in some sense- that 002 and 016 were supposed to be together, and he would do whatever he need to get them together.
