The poem opens with vibrant imagery describing the tigers pictured in Aunt Jennifer's craftwork. The reference to a "screen" in line 1 signals to the reader that these tigers are part of a tapestry or canvas—a hint that is confirmed in the second stanza, which describes the actual act of Aunt Jennifer's working with a needle and wool.
The words used to describe the tigers establishes them as bold and confident. They are "bright" and colored "topaz," a translucent yellow hue associated with the gem of the same name (topaz can also be a vivid blue in color, which would add a fantastical element to the tigers' appearance). Associating the tigers with a glittering precious stone gives them value. The use of the verb "prance" then suggests a light-hearted, proud, springing action; the wild cats don't simply walk, they stride proudly and with confidence.
The vivid imagery continues as the topaz tigers are set against a color-contrasting backdrop, "a world of green." This color suggests a natural setting, such as a forest, which the tigers are denizens—inhabitants—of. The use of consonance with the /z/ sounds in the phrase "topaz denizens" emphasizes this sense of belonging, asserting the animals as permanent residents in the world of green.
As the rest of the poem will make clear, this "world of green" is vastly different from the world that Aunt Jennifer inhabits: While the tigers roam freely in their green world—ironic, given that they are technically "trapped" in a tapestry screen—Aunt Jennifer is trapped in the world of her oppressive marriage.
The use of the possessive case with "Aunt Jennifer's tigers" reminds the reader that the tigers would not exist without Aunt Jennifer. She has made the "world of green" that these proud creatures prance through, putting her in the role of a God-like creator. Although the poem goes on to describe Aunt Jennifer as an anxious, "terrified" woman, these first three words serve to remind the reader of this meek woman's power—namely, the power of creativity and creation. She has crafted the world of green that the tigers live in.
The first two lines of the poem also set up a rhyme scheme that will continue throughout, with the perfect end rhyme of "screen"/"green." The rest of the poem will uphold the use of rhyming couplets, presenting a rigid regularity that reflects the rigid confines of Aunt Jennifer's marriage. (This formalism will ultimately be disrupted in other ways, however, reflecting the subversive nature of Aunt Jennifer's handiwork.)
The speaker of the poem is not introduced in the first lines or at any other point in the poem. "Aunt Jennifer's Tigers" is told from an anonymous outsider's point of view, describing Aunt Jennifer and her tapestries. Although the speaker can be presumed to be a relative, given that they use the terms "Aunt" and "Uncle," this is in no way confirmed at any point in the poem. No details about the speaker—not their gender, age, nor precise relationship to Aunt Jennifer—are ever revealed.