Is this a metaphor?: "Grim Reaper had put up his tent on our doorstep!... Stella. Belle Reve was his headquarters!"

Nope!

https://literary-devices.com/
Check among these, and let me know what you decide: metaphor, hyperbole, personification, simile, alliteration

Yes, the phrase "Grim Reaper had put up his tent on our doorstep!" is a metaphor. It is comparing the presence of death (symbolized by the Grim Reaper) to the act of setting up a tent on someone's doorstep, signifying that death is looming close by.

The phrase "Stella. Belle Reve was his headquarters!" also contains a metaphor. It compares the residence of Stella (Belle Reve) to the headquarters of the Grim Reaper, suggesting that death is centered or based at that location, emphasizing its significance or impact on the characters.

To determine whether a statement is a metaphor, we need to understand the literal meaning of the words and phrases used and then evaluate whether they are being used figuratively.

In the statement, "Grim Reaper had put up his tent on our doorstep!... Stella. Belle Reve was his headquarters!", it appears that the "Grim Reaper," "tent," "doorstep," "Stella," and "Belle Reve" are all being used metaphorically.

The Grim Reaper is a personification of death, often portrayed as a hooded figure wielding a scythe. Therefore, saying that the "Grim Reaper had put up his tent on our doorstep" is a metaphorical way of expressing that death or mortality has arrived or is imminent.

Similarly, "Stella" and "Belle Reve" are references to characters from Tennessee Williams' play "A Streetcar Named Desire." In the play, Stella and Belle Reve symbolize beauty, elegance, and a world of fantasy. Using these references metaphorically suggests that the somber presence of death is contrasted with the beauty and fantasy of the characters and setting from the play.

Overall, the statement contains multiple metaphors to convey the idea of death's presence and its stark contrast with the world of beauty and fantasy.