The speaker describes watching someone go through an overdose, and the poem opens with a single word: "Fear." That word sets the tone right away. The speaker sees it in the person's eyes, which look lost and confused. She doesn't know where she is or what's happening to her, and the short, plain lines make her disorientation feel immediate.
Then the poem turns. The speaker says she knew "only one thing," and the poem pauses on it, calling it "the most important thing" before revealing it: "We were all there for her." After all the fear and uncertainty, this last line is steady and reassuring. It is the only moment of comfort in the poem, and it stands alone on its own line.
The mood is tense and anxious at first, then softer and protective. The speaker doesn't dwell on details or blame anyone. What matters is that, in a frightening moment, the person wasn't alone.