Inversion results along the fibril–background set labelled with f3 in Fig. 7; top panels: fibril (red) and background (grey) overplotted on intensity maps of the RoI marked with a solid-lined box in Fig. 1 in the continuum and Ca II K summed light. The head, midpoint and tail of the structures are marked similarly to Fig. 4. The average observed and synthesised line profiles along the structures are shown in the middle row panels. The inversion results of the temperature, line-of-sight and microturbulence velocities for each individual pixel along the path of the structures are plotted with the washed-out lines and the average profiles are shown with the bold lines in the bottom panels. An animated version of this figure showing the fit of each indiviudual line profile along the fibril is available online.