A quatrain is a verse with four lines, or even a full poem containing four lines, having an independent and separate theme. Often one line consists of alternating rhyme,
existing in a variety of forms. We can trace back quatrains in poetic
traditions of various ancient civilizations, such as China, Ancient
Rome, and Ancient Greece; and they continue to appear in the
twenty-first century.
When words within a line of poetry have the same sound is called, internal rhyme I believe
Foreshadowing is when an author uses symbolism, an event, a small detail, or even a part of dialogue to be a warning or indication of a future event. An author might use this because they want to give the reader knowledge about a future event or to tease them.