I see this story going one of two ways, assuming we can take Hiro becoming half-Klaxx for granted next episode given the animation director's tweet:
1. Hiro is emotionally devastated, he uses Ichigo horribly to try and distract himself from the pain and hospitalizes her in the process- becoming half klaxx. During the multiple Franxx waves reducing the large Klaxosaur numbers around the Gran Crevasse he makes a name for himself with his obscene skill and technique, such that Papa starts throwing pistils at him to use with a mass produced Franxx unit. 02 hears rumors about a stamen with horns, claws, and fangs who is killing pistils and becomes distraught over what she has done to her Darling. That she needs to contact him in order to somehow save the boy she loved before he's lost completely, that she starts to appreciate how Hiro in turn would despair over her and what she has done. She in turn must also assume you can still be human even if you're a "monster", that the alternative would mean she killed Darling in truth.
2. Hiro is emotionally devastated, and still uses Ichigo, but in becoming half Klaxx finds new resolve. He starts acting the paragon, and while Papa starts throwing pistils at him to use he never kills them. Just swaps them out when they are too injured to continue. Every pistil he gets paired with he treats in a princely manner, and begins their relationship by bequeathing them a name. Making them an individual, raising them above the other pistils and stamens. 02 starts hearing rumors of a stamen with horns and fangs like her that no pistil can pilot with for more than a couple runs- but instead of fear and hate they treat him with awe. The other pistils are actually envious of those able to pilot with him, they come out of the experience changed people. That she realizes being a monster was no excuse for her behavior, and that she has to contact Hiro to make amends.