Trait domains of the five-factor model (FFM) are not orthogonal, and two meta-traits have often been estimated from their covariation. Here we focus on the Stability meta-trait, which reflects shared variance in conscientiousness, agreeableness, and neuroticism (inversely). It has been hypothesized that Stability manifests, in part, due to individual differences in central serotonergic functioning. We explore this possibility in a community sample (N=441) using a multiverse analysis of multi-informant FFM traits and Stability predicting individual differences in central serotonergic functioning, as assessed by change in serum prolactin concentration following intravenous infusion of the selective serotonin reuptake inhibitor, citalopram. Results were mixed, showing that trait neuroticism, agreeableness, and conscientiousness, as well as the Stability meta-trait, are significantly associated with prolactin response, but that these findings are contingent on a number of modeling decisions. Specifically, these effects were non-linear, emerging most strongly for those highest (lowest for neuroticism) on the component traits.