Finally, someone thinks the same way I do. After Yuki caught his mother having an affair with his grandfather, he should be the next to experience his mother's lust. Lizana might even feel a stronger connection with her son than with her father-in-law. Roberto might get jealous of the two of them, since Lizana would be completely focused on Yuki. This could open the door for a relationship between Roberto and his granddaughter. It would be a rivalry between Yuki and Lizana versus Roberto and his granddaughter. All done in secret.