Color the skin with a light lavender marker. Make sure the shape is irregular, and smudge the edges of the mark with a tissue or finger.
Add a line of olive green around the bottom edge and smudge it.
Draw over the green with the lavender and smudge it.
Add a line of baby blue to the top of the bruise and smudge it.
Add a couple of dots of dark purple to the middle of the bruise and smudge it. Cover it with lavender marker and blend with a finger.
Add a little light yellow-brown right next to the olive area; smudge it and cover it with lavender.