Dr. FRANXX

Dr. FRANXX (フランクス博士) is the old man responsible in constructing FRANXX.

Appearance
He has the appearance of an older man, sporting grey hair and a mustache. He normally wears a white coat similar to the other adults in the setting, along with white gloves, and he also uses a cane. Half of his face and several digits of his hand are mechanical.

Personality
He has the nature of a calm individual, with a lecherous streak as shown when he groped Nana. He takes pride in his creations, but does seem rather disinterested in the formal procedures, such as when he was asked to attend the ceremony.

He's also quite adventurous, never sitting in one place. He always tries to find the best seat whenever there's a big battle.

History
He appears in Episode 1, escorting Zero Two along with the cargo needed for testing that he intends to carry out at the Thirteenth Plantation. When the Mohorovic-class Klaxosaur appeared, he observed it before Strelizia dispatched it.

In a flashback in episode 13, he is shown to have run experiments on Zero-Two, and later erasing her and Hiro's memories.

Zero Two
The doctor seems to have an almost parental relationship with Zero Two, given the tone he speaks to her with and how casually he accepts her behavior.

Hiro
Hiro had survived 3 sorties with Zero Two, which makes him an "interesting specimen".

During their personal meeting in episode 7, he says that "that boy (Hiro) could be the one to fulfill her (Zero Two) wish".

In episode 15, they had another chat. He remarks about how Zero Two is such a marvelous creation, yet is always so lonely, like a Klaxosaur. Hiro objected, saying that she's human. Intrigued, the doctor turns around to look at Hiro. He says that he had thought she (Zero Two) may have finally found a partner as Hiro prepares to leave for Zero Two.

Papa
Papa refers to Dr. Franxx as Werner. Dr. Franxx refers to Papa and the sages as "silly hellcats".

Trivia

 * Dr. FRANXX is the one who named and classified the robots as FRANXX but is unclear if it came from his name or if his name came from naming the robots.