  We present high-resolution observations of a flaring event in the M8 dwarf vB
10 using the near-infrared Habitable zone Planet Finder (HPF) spectrograph on
the Hobby Eberly Telescope (HET). The high stability of HPF enables us to
accurately subtract a VB 10 quiescent spectrum from the flare spectrum to
isolate the flare contributions, and study the changes in the relative energy
of the Ca II infrared triplet (IRT), several Paschen lines, the He 10830 \AA~
triplet lines, and select iron and magnesium lines in HPF`s bandpass. Our
analysis reveals the presence of a red asymmetry in the He 10830 \AA~ triplet;
which is similar to signatures of coronal rain in the Sun. Photometry of the
flare derived from an acquisition camera before spectroscopic observations, and
the ability to extract spectra from up-the-ramp observations with the HPF
infrared detector, enables us to perform time-series analysis of part of the
flare, and provide coarse constraints on the energy and frequency of such
flares. We compare this flare with historical observations of flares around vB
10 and other ultracool M dwarfs, and attempt to place limits on flare-induced
atmospheric mass loss for hypothetical planets around vB 10.
