All of them are Assassin class Servants, and they can operate as if they have a hive mind. Though, they are separate individuals, and do have their unique traits. Ortlinde is the least openly emotional, Hildr is the most human-like, Thrúd is the most restrained of them, Rindr is a bit airheaded and does things at her own pace, Ölrún is especially good at reading a room and avoiding unnecessary conflict, and Geirskögul is an individualist who strives to be true to herself.