The Middle voice indicates that someone is acting on themselves or for their own benefit or by themselves. "He washed himself." There are several forms. See this article.

The Middle Passive voice is a verb form that can be either the middle voice or a passive voice. In transitive verbs, it acts as a passive: "he is washed" but for non-transitive verbs, it is acts as the middle voice "he rested for his benefit" or "he rested himself."

1. Reflexive: "I wash (myself)." This reflexive sense could also carry a sense of benefaction for the subject, as in the sentence "I sacrificed a goat (for my own benefit)."
2. Reciprocal: "to fight" (with active) vs. "to fight each other" (with mp).
3. Autocausative: describes situations where the subject causes itself to change state.
4. State of Being. With verbs relating to standing, sitting, reclining, being afraid, being ashamed, and being pleased, etc.
5. Intensive: "to be a citizen" (with active) vs. "to do the duties of being a citizen" (with middle).
6. In deponent verbs that have not active form, for example, "to follow."
7. Combined with the subjunctive to form the future tense of the verb "to be" in Classical Greek.

Subjunctive Mood