Miquella is a girl, here's why

Evidence that Miquella is a boy:

  1. He's referred to as Malenia's twin brother and the game uses he/him pronouns.

Evidence that Miquella is a girl:

  1. She's arguably the most feminine looking character in the game. She wears a dress and has long blond hair with braids.
  2. She's an Empyrian. All other Empyrians in the game are female, why would Miquella be the only exception?
  3. Mogh wants to be her king consort and start a dynasty with her. That's kind of hard if they're both dudes.
  4. In the cut content, it's confirmed that she's actually St. Trina. St. Trina is female.
  5. Her name ends in "a" which usually denotes female in this game, and in the real world.

There seems to be more evidence supporting the Miquella is a girl theory. But it's possible she/he is a hermaphrodite. Since it was revealed that Marika is Radagon, gender bending is a thing. My theory is that Miquella was either born a boy, or his/her gender was ambiguous at birth and they declared him a boy. But he always felt like he should have been a girl. Hence the way he dressed and wore his hair. I wouldn't put it past GRRM to put a trans or hermaphrodite character in his story.

In fact the whole cocoon thing could have been a means for him to emerge as a woman, St. Trina. It's sort of like the empyrian version of a sex change operation. But unlike real life sex change operations, empyrians can actually biologically change their sex (as evidenced by Marika/Radagon). So it was generally understood that Miquella would have a womb and indeed be able to bear children after emerging from the cocoon had the plan worked, hence why Mogh wanted to be Miquella's King Consort and start a dynasty with her.

Of course, the plan didn't work, and Miquella actually looks like this now: https://i.imgur.com/SPnXR8L.jpg but hey, at least he's all grown up and Mogh doesn't look like as much of a scumbag now.