Myself, the same, on my own
Three neighbouring tools English mixes up: ο εαυτός μου (myself, as object), ο ίδιος (in person / the same), μόνος μου (without help).
ο εαυτός μου — the reflexive object
A real masculine noun that declines: Βλέπω τον εαυτό μου στον καθρέφτη (I see myself), Μίλα στον εαυτό σου με καλοσύνη. Often the passive is enough (πλένομαι) — τον εαυτό μου steps in for emphasis or after prepositions.
ο ίδιος — in person, or the same
With the article before the noun: the same — το ίδιο λάθος (the same mistake). After the noun or alone: in person — ο ίδιος ο πρόεδρος (the president himself). Bare το ίδιο: “the same thing” — Κι εγώ το ίδιο.
μόνος μου — unaided
Agrees with the subject + possessive: Το έφτιαξα μόνος μου (I fixed it by myself), Η Άννα ταξιδεύει μόνη της, Τα παιδιά ντύνονται μόνα τους. Not to be confused with μόνο (only).
Your turn
Choose the correct form.