Synthetic He I and He II line profiles from our spectroscopic model, corresponding to selected triangles with given temperatures and RVs. They demonstrate where lines form in our model. For a fast-rotating star, the pole is substantially hotter than the equator. The central line (RV = 0) corresponds to the pole, other lines originate from the equator (RV ≠ 0). He I and He II lines form at different locations on a fast or critically rotating star due to strong temperature gradients. He I lines have the lowest intensity on the poles, while He II lines have the highest intensity at the poles. He I lines are less intense at the pole, while He II lines are less intense on the equator. The grey points indicate the He I lines for clarity.