Use a blender or food processer to blend up the banana, watermelon and berries. If you don't have a blender or food processor, you can use a vegetable masher to mash it all up.
Pour blended fruit into a mixing bowl.
Add egg and whisk lightly.
Add flour and mix to combine.
The batter will be a lovely deep purple, thanks to the blueberries.
Depending on the size of the banana, consistency of the batter may vary. If you pick it up with a spoon it should run off in a fairly thick drizzle. If you feel that the batter is too thick, add a splash of water or milk and mix it in. If you think it's too runny, Add more flour a little bit at a time until it seems right.
Heat a little butter or olive oil in a frying pan over medium heat.
Add large spoonfuls of the batter to the pan, evenly spaced.
Cook until golden brown underneath and the top is just starting to set.
Flip pancakes with a spatula and allow other side to brown.
Once both sides are golden brown, remove from pan.
Allow to cool for a few minutes and serve.