I went into Sirens thinking here's a fluffy nonsense deal and by the end was just entirely rapt by the realness of how literally EVERY character behaved? like it was entirely believable and I also did NOT expect it

Exactly the same. I kept repeating “I am so impressed by this show!” I loved the way it absolutely refused to make anyone the villain.

AGGRESSIVELY ANTI-VILLAIN which I was just floored by, even by the end I was like well I can't even really dislike Kevin Bacon here

And you knew you were going to get good performances out of Moore and Bacon, and Meghann Fahy has been sneaky good for a while, but Milly Alcock was a revelation