The poem is a single open question, and it hangs in the air without an answer. The speaker wonders whether "we or others" will suddenly flare up, "break into sudden scarlet." The title, "In the red," points two ways at once: the colour of warning and blood, and the idea of being in debt or in danger.
The second half compares that burst of colour to "inks best for danger," the sort of ink you might reach for when something urgent has to be marked. Then comes the oddest image: "where the pen stood by." The pen waits, ready but not yet writing, as if it is watching for the moment trouble arrives.
The mood is uneasy and quietly alert. The speaker doesn't announce a crisis; they only ask if one might come, and whether it will touch them or someone else. The lack of punctuation and the short lines add to the feeling of holding your breath. It reads like a warning that hasn't yet been written down.