Speaker
The title suggests that the speaker is Aunt Jennifer's niece. However, during the poem, the speaker seems distant from the action. She describes the scene in the third person, and calmly predicts her aunt's death. This lack of attachment suggests that the speaker is probably speaking from a place of remove, perhaps long after this scene took place. As readers, we know that by the time of this poem, the speaker has come to disapprove of Jennifer's marriage, but we also know she wasn't able to do anything for her aunt other than describe her life.
Aunt Jennifer
Aunt Jennifer is portrayed as a woman dominated by her husband. Her fluttering hands struggle even to pull a needle through fabric, and she dies terrified. We aren't lead to believe that Jennifer was always this way: instead, Rich emphasizes that Jennifer was weighed down by her marriage, and "mastered" by its endless ordeals.
The Uncle
Jennifer's husband looms in the background of the poem despite never appearing directly in the text. It's possible that he's abusive, but it is also possible that Rich is merely writing about the routine, ordinary power husbands hold over their wives. Either way, an absent Uncle is still able to confine Aunt Jennifer within fear and weakness.
The tigers
Rich characters the tigers as "chivalric," or having the characteristics of traditional knighthood. She also repeatedly emphasizes their fearlessness, as well as their joyful, free movement through the world. They are a foil to Aunt Jennifer, who is terrified and confined.
