9'ε

 is a character in DARLING in the FRANXX.

Appearance
Epsilon has purple hair and grey eyes and wears the standard 9’s uniform. Of the four stamens, he is the tallest in stature, as shown in his first appearance with the entire Nines squad in Episode 12.

Episode 06: DARLING in the FRANXX
Strangely enough, Epsilon does not appear in the Nines cameo in Episode 6. It's quite worth mentioning that the other three stamens present above the site of the plantation kissing (Alpha, Beta, and Gamma) are the copilots of the triplet stamens.

Episode 12: The Garden Where It All Began
Epsilon makes his first cameo appearance, this time alongside the rest of his squadmates, including Gamma, Delta (his FranXX partner, as is shown in episode 15), and Zeta (along with her two identical counterparts).

Episode 14: Punishment and Confession
Epsilon makes his third cameo appearance, waiting with their leader to welcome back a sorrowful Zero Two to their fold.

Episode 15: The Bird that Shares Wings
Epsilon appears in the Battle of Gran Crevasse, and he is the first stamen of the Nines faction shown to be in the reverse position, as his partner Delta gleefully tells the klaxosaurs, "You're boring. Entertain us more!"

Etymology
Similarly to Zero Two, he received the name from Papa. Epsilon is a letter in the Greek alphabet.

Trivia
  9'ε