When fruit is heated through it tenderizes and amplifies the sweet juicy-ness. Many prepare grapefruit for the broiled by topping with some form of sugar - granulated, honey, agave…this enhances the chard-ness. Yet, the act of heating fruit already amplifies it’s sweet flavor! So, I go without the added sugar (because fruit is a natural source of sugar). Broil on low or high - depending on your timeframe.