What cocktails can I make with light rum, dark rum, orange juice, and passion fruit syrup?

It sounds like you're in the mood for a tropical cocktail with both light and dark rum, orange juice, and some passion fruit syrup. While there isn't an exact match in the list provided, a cocktail that comes close and can be a great base for what you're seeking is the Rum Louis.

The Rum Louis cocktail features a delightful blend of pineapple juice, orange juice, and grapefruit juice, along with both white and dark rums. Although it lacks passion fruit syrup, the assortment of citrus juices, including orange juice, offers a bright and zesty flavor profile. You could easily add a touch of passion fruit syrup to the mix to create your ideal libation.

This drink boasts a high rating of 4.9/5, which speaks to its well-balanced and refreshing taste. Served in a highball glass, it promises a visually appealing presentation that adds to the overall enjoyment.

Feel free to use the Rum Louis as inspiration and modify it to include your desired passion fruit syrup for that perfect tropical cocktail!