Communities of Yuan-ti that make their homes in swamps tend to enjoy the bountiful water and life around them and create gregarious, thriving, and colorful societies rich with arts and culture. They harvest not only food, but art supplies and crafting resources from the vibrant ecosystems around them and more often than not, have strong hospitality traditions, welcoming those passing through their communities with friendly enthusiasm.
This outlook frequently brings them into conflict with other swamp-dwelling denizens of less-friendly intentions, however, and the conflicts between swamp yuan-ti and beings such as black dragons or hags can get vicious indeed. This duality has led to swamp yuan-ti communities being like a stone fruit such as a mango or peach: they are colorful and sweet on the outside, but bite down far enough on one and you will find a hard, unyielding core.
Yuan-ti and those they take in (who can sometimes wind up outnumbering the yuan-ti) from such a society often wind up as hardy, well-rounded, and charismatic people with a wide variety of life experiences and a streak of toughness and self-sufficiency undergirding it all.
Cultured and Creative. You gain proficiency with a musical instrument and a toolkit of your choice.
Swamp Swimmer. You gain a swim speed equal to your walking speed and you have advantage on stealth checks in water.
Hardy and Resolute. You gain an expertise die on saving throws against poison, disease, and effects that would cause you to become frightened.
Languages. You can speak, read, write, and sign Common and two additional languages of your choice.