The trinity

A close friend of mine has started making a comic about me, him and an other friend of ours.
Him, being the guy in the top left corner (Roel).
Me, being the guy in the middle (Joshua) and the other guy (Senne).
It happens to come in handy that he's rather good in sketching and coming up with ideas and I'm semi-good in tracing and coloring stuff, hence we're working together to make this comic.
Still I've only just begun with using the path tool and I have the occasional problem of getting white dots if I try to fill an area closed with the path tool, any suggestions anyone?

See below:
The trinity (W.I.P. ;go figure...)