Selkies, Sirens, Swan Maidens and Otherworldly Brides
A common motif in British folklore is that of an otherworldly female, who is somehow captured or charmed by a mortal man to be his bride. The females are often therianthropes, that is shape-shifters, who seem to be part human and part animal, but their main attribute is always as an entity from a metaphysical otherworld, interacting with consensus reality in order to bridge the gap between the natural and the supernatural.
The Fishermen and the Siren by Knut Ekwall (1843–1912) (Public Domain)
These therianthropic females take many forms, such as Selkies (humanoids masquerading as seals), mermaids, and swan-maidens, and can also appear as magical women without any animal attributes, such as the lake faeries, but they are always found in bodies of water, a configuration that proves important in any attempt to interpret these folkloric motifs. The standard scheme of the stories is that the female is lured from her watery existence by a male, either through a ruse or by charm. They are married and will usually have children together. But at some point, a taboo is broken or the female is mistreated, and she deserts her husband to return to the water, which always seems to represent the portal between the physical world and a non-material reality.
