We regulate others emotions through our own

Researchers studying intra- and inter-personal emotional regulation on fMRI show that we use our own experience of emotion when we help someone else processes theirs.

“Both intrapersonal and interpersonal emotion regulation were associated with a largely overlapping network of brain areas, incorporating the bilateral lateral frontal cortices, the pSMA, and left TPJ. Frontal activation is consistent with the findings of previous studies on the cognitive control of one's own emotion and suggests that both tasks involved a degree of control over one's own emotional experience.”

Hallam, G. P., Webb, T. L., Sheeran, P., Miles, E., Niven, K., Wilkinson, I. D., ... & Farrow, T. F. (2014). The neural correlates of regulating another person's emotions: an exploratory fMRI study. Frontiers in human neuroscience, 8, 376.