Plot: Siren in the Well

Should any male character get within 60 feet of the surface of the well, they must succeed on a DC 12 Wisdom saving throw or be affected by the Song of the Well as Shavae, the well siren, has begun her song. If more than one target fails the Wisdom saving throw, she will either choose the target who failed by the most, or the target with the highest Charisma (DM’s choice), and the others will be released from her enchantment. Should the charm somehow be broken, she will sing again, as those who were charmed before are not technically immune to her song unless they are deaf or otherwise immune to her song. Should all possible male targets pass their saving throws, she will call out for aid, claiming she is trapped down the well, and has been here for a very long time. She will claim her hands are hurt, and so cannot climb up any ropes or other lowered objects. Shavae is quite deceptive, and will use whatever tools she has to lure a target into the well.
Characters who either throw themselves in the well, or otherwise climb into the well, will find the descent easily 50 feet deep. At the end of this 5 foot diameter, 50 foot deep cylinder, the well opens up into a larger cavern. From the bottom of the well it’s a 20 foot drop to the surface of a pool, 30 feet in diameter and a further 20 feet deep. Strange grasses of bright green, pink and yellow sway at the bottom of this clear pool, and the scattered speckles of copper coins and other minor treasures twinkle in the light from above from the bottom of the pool.
Those who haplessly throw themselves into the well, or otherwise fall into it, will land with a splash into the water, suffering only 1d6 bludgeoning damage from the fall due to the softer impact and the welcoming cool water of the pool. Beside the pool, growing up from the bottom as if it were meant to, is a thick stemmed and sturdy creeping vine or plant filled with leaves of green, pink and yellow. Its upper leaves are just catching some of the sunlight as it beams from above. Swimming happily through the clear waters of this pool is what looks to be a beautiful female humanoid with the lower half of a fish. Her long pink hair spills behind her as she swims gracefully below the water, propelled by an elaborate pink, purple and blue-scaled fish tail. Black pupils set in golden yellow eyes stare at whoever falls into her pool. She will approach charmed characters slowly and methodically, smiling all the while.
If a lone target falls into the well, and is the recipient of the Kiss of the Well, and remains with her in this pool frolicking and romancing for 1 hour, she will attempt to take them to the bottom of the pool. If the target is still charmed, or comes willingly, she will try to take the target to the Feywild to mate. To do so, the character will have to succeed on a DC 15 Charisma saving throw to successfully navigate the breach. If they succeed, the target will disappear into the Feywild until the next full moon, reappearing in the prime material plane at a place of the DM’s choosing. If the character fails this saving throw, attempts to escape, or attacks the Shavae in any way, she will fly into a rage and attack.