  Photometric and spectroscopic observations of type Ia supernova (SN) 2017fgc
which cover the period from $-$12 to +137 days since the $B$-band maximum are
presented. SN 2017fgc is a photometrically normal SN Ia with the luminosity
decline rate, $ \Delta m_{15} (B)_{true} $= 1.10 $ \pm $ 0.10 mag.
Spectroscopically, it belongs to the High Velocity (HV) SNe Ia group, with the
Si II $\lambda$6355 velocity near the $B$-band maximum estimated to be 15,200 $
\pm $ 480 km $s^{-1}$. At the epochs around the near-infrared secondary peak,
the $R$ and $I$ bands show an excess of $\sim$0.2 mag level compared to the
light curves of the normal velocity (NV) SNe Ia. Further inspection of the
samples of HV and NV SNe Ia indicates that the excess is a generic feature
among HV SNe Ia, different from NV SNe Ia. There is also a hint that the excess
is seen in the V band, both in SN 2017fgc and other HV SNe Ia, which behaves
like a less prominent shoulder in the light curve. The excess is not obvious in
the B band (and unknown in the U band), and the color is consistent with the
fiducial SN color. This might indicate the excess is attributed to the
bolometric luminosity, not in the color. This excess is less likely caused by
external effects, like an echo or change in reddening but could be due to an
ionization effect, which reflects an intrinsic, either distinct or continuous,
difference in the ejecta properties between HV and NV SNe Ia.
