D&D 5E (2024) Feywild technically doesn't mention the Seelie and Unseelie Court

[MechaTarrasque]

At least some of the fey are created by strong emotions (Red Caps come to mind), so in theory the "positive" emotions (or the ones people generally desire to experience) could be one court, and the "negative" ones (or the ones people generally desire not to experience) could be another court. Of course, too much of a good thing can be bad for you...

I tend to play up the melodrama when my campaign enters the 'Wild.

Since the Shadowfell is about suppressed emotions, I treat fey there as a kind of undead, trying to eat the emotions of other beings (psychic damage and doing damage to Cha scores instead of regular damage/other attribute damage). If a 'Fell fey kills a 'Wild fey, the 'Fell fey goes back to being a 'Wild fey and the former 'Wild fey wakes up as 'Fell fey 24 hours later. Non-fey are not as useful, but if a 'Fell fey kills a PC (after making them feel a strong emotion), that will probably be enough for them to change back to 'Wild fey.

 

[Corinnguard]

Fey are born from the ephemera of dream, and thus are fickle and capricious creatures, capable of turning from mirth to malice in an instant. Fey have no fixed nature and thus must live by their ideals and their oaths lest they unravel themselves. Nonetheless different fey may find in any of the courts or some will change courts according to the seasons, mood or personal whim.

Level Up has it where the Fey are members of the Dreamborn heritage. The Feywild in Level Up is called the Dreaming.

 

[Paul Farquhar]

I associate the seelie with spring and summer, and emotions like passion, confidence, love, lust, jealousy and impulsiveness - not necessarily all positive.

The unseelie I associate with autumn and winter, and emotions like depression, melancholy, uncertainty and mindfulness.

The alien legal code is the same in both courts.


The Shadowfell is the realm in which all emotions are drained away, making it particularly deadly to fey.

 

[Yaarel]

The unseelie I associate with autumn and winter, and emotions like depression, melancholy, uncertainty and mindfulness.

I feel these aspects of autumn and winter (foreboding, depression, scarcity) relate to dying and death directly.

By contrast, autumn and winter can be life-orienting. Autumn comes with abundant harvests. Winter is exhilarating beauty and a time for indoor projects and arts, and spending time together.

When I think of unseelie, I associate boogie monsters, goblins, spooky aspects of nature, trolls, terror. In other words, the destructive, deathly, aspects of nature and psychology.

Each season − winter, spring, summer, autumn − includes both seelie and unseelie aspects.

 

[Tonguez]

I feel these aspects of autumn and winter (foreboding, depression, scarcity) relate to dying and death directly.

By contrast, autumn and winter can be life-orienting. Autumn comes with abundant harvests. Winter is exhilarating beauty and a time for indoor projects and arts, and spending time together.

When I think of unseelie, I associate boogie monsters, goblins, spooky aspects of nature, trolls, terror. In other words, the destructive, deathly, aspects of nature and psychology.

Each season − winter, spring, summer, autumn − includes both seelie and unseelie aspects.

IMC I have a Unseelie Spring Hag "Nanny Blossomthaw" The Mother of Renewal, the Spring Thaw, the Petal Crone. She represents the Spring thaw. When the Cailleach lays down her mantle of frost and the snows retreat, the earth awakens to the melting ice and the muddy soil drinks deeply of decay. It is Nanny Blossomthaw who rises laughing from that thaw. She is the first warmth, the soft rot, and delights in every bud that forces its way through old bones, every worm that turns the dead to loam. To her, life is the inevitable outcome of decay- chaotic, relentless and all consuming abundance.

Nanny Blossomthaw adores mortals. She calls them her little seedlings, and will adopt an entire village as her garden. She waters their spirits with mirth and song, prunes away sorrow and sickness, and encourages growth in every sense — emotional, artistic, and physical. But she cannot bear stagnation and dreads despondency. When stength withers, she cuts it away, when joy fades, she replants.
Under her care, a village becomes a vibrant garden of color and excess: lovers dance till they collapse exhausted, artists paint the horizon with their endless dreams, crops, weeds and brambles grow wild through the streets, and flowers bloom from every surface - including the flesh of the withered and the dead. By the end the village becomes a garden of bright smiling blossoms growing in a field of bones.

 

[Corinnguard]

IMC I have a Unseelie Spring Hag "Nanny Blossomthaw" The Mother of Renewal, the Spring Thaw, the Petal Crone. She represents the Spring thaw. When the Cailleach lays down her mantle of frost and the snows retreat, the earth awakens to the melting ice and the muddy soil drinks deeply of decay. It is Nanny Blossomthaw who rises laughing from that thaw. She is the first warmth, the soft rot, and delights in every bud that forces its way through old bones, every worm that turns the dead to loam. To her, life is the inevitable outcome of decay- chaotic, relentless and all consuming abundance.

Nanny Blossomthaw adores mortals. She calls them her little seedlings, and will adopt an entire village as her garden. She waters their spirits with mirth and song, prunes away sorrow and sickness, and encourages growth in every sense — emotional, artistic, and physical. But she cannot bear stagnation and dreads despondency. When stength withers, she cuts it away, when joy fades, she replants.
Under her care, a village becomes a vibrant garden of color and excess: lovers dance till they collapse exhausted, artists paint the horizon with their endless dreams, crops, weeds and brambles grow wild through the streets, and flowers bloom from every surface - including the flesh of the withered and the dead. By the end the village becomes a garden of bright smiling blossoms growing in a field of bones.

I can imagine that she is a Patron to several green-thumbed warlock/druids.