intervene

To become involved in a situation, so as to alter or prevent an action.

The police had to be called to intervene in the fight.

Nature film-makers are discouraged from intervening in the events they are attempting to capture on film.

To occur, fall, or come between, points of time, or events.

An instant intervened between the flash and the report.

I hadn't seen him since we were in school, and the intervening years had not been kind to him.

To occur or act as an obstacle or delay.

Nothing intervened to prevent the undertaking.

For while so near each other thus all day Our task we choose, what wonder if so near Looks intervene and smiles, or object new Casual discourse draw on, which intermits Our dayes work brought to little,

To say (something) in the middle of a conversation or discussion between other people, or to respond to a situation involving other people.

Young Scarfe stared, astounded. “You haven’t met before,” Mrs. Gould intervened. “Mr. Decoud—Mr. Scarfe.”

“That sounds suspiciously like bigotry to me,” intervened Maitland, sweetening his impertinence with a dimpled smile.

To come between, or to be between, persons or things.

The Mediterranean intervenes between Europe and Africa.

1668, Joseph Glanvill, Plus Ultra, or, The Progress and Advancement of Knowledge since the Days of Aristotle, London: James Collins, Chapter 11, p. 79, How defective the Art of Navigation was in elder Times, when they Sailed by the observation of the Stars, is easie to be imagin’d: For in dark weather, when their Pleiades, Helice, and Cynosura were hidden from them by the intervening Clouds, the Mariner was at a loss for his Guide, and exposed to the casual conduct of the Winds and Tides.