No need for sugar, fruit has a lot of sweetness in it already.
When I lived on Whidbey Island, the famous Greenbank Farms there was still in business growing their delectable loganberries and making Whidbey Loganberry Liquor. During a tour I learned they produced it by plunging fresh picked fruit directly into vats of icy vodka, which was then kept refrigerated for a month before straining and bottling. They felt that keeping it cold helped preserve the full range of delicate flavors and aromatics that are characteristic of fresh fruit.
Since then I have made many fruit-infused liquors, including a ridiculously delicious fig potion. I typically do not add sugar to the bottle, preferring to add any desired additional sweetness before serving with a simple syrup I make from cane sugar. First, I believe that keeps the flavors brighter, and second, it allows adjusting the sweetness to taste. Otherwise, when concocting a beverage with fruit juices and an already sweet liquor it's easy to end up with an overly sweet drink.