DISCLAIMER:Any theory that is posted is just in fun. I am posting these as a reader myself, imagining I'm in your shoes and what you would think. None of these theories have potential spoilers in them and can be taken how you want to take them. They may or may not be true, but that's up to you to decide.
Lord Ahriman is extremly suspicious what can I say? He is like Count Dracula; he wears a fake smile and prancing around with skin like a vampires. Someone ought to see if he and Lord Bolton are related. This theory is a bit of a stretch well actually the second part of the theory is, the first part is almost set in stone. So let's get into it.
What is Lord Ahriman doing? We see Ahriman appear in the prologue of AMfD, he recruits a woman and takes her down to the dungeons of the Red Keep where she is led to her death. What the girl sees is 'a sleeping giant with syringes sticking out of each part of its body, springing from inside and outside like vines from a frenzied plant'. This giant of a person is being operated on by Lord Ahriman, and May will be another asset to him, but why is he operating on some giant. Where did he find this man? Of course he may just be some random Goliath he found dead in the street but it isn't that, the clues are there to be seen.
We do know about a recently dead giant of a person. The Mountain. Killed in The Battle of King's Landing, Ahriman approached Aeyron asking for possession of his body and Aeyron let him. We can only assume that the body that Ahriman has, is the Mountain's. The giant roars throughout the story and reemerges into the land of the living around Edmund I. When Edmund sees him, he describes him as 'Eight-foot tall, legs thicker than castle walls, a torso larger than a door. His armour was the same of the Kingsguard but Edmund would never have expected the armour could be fashioned for so large a person'. Ignis also remarks on the height of the giant. Who also is remarked to be enormous? The Mountain. Ignis's notices his height and he is described as ' the closest thing they had to a living giant', The Mountain also states himself that 'he was by far the biggest at beyond seven foot'. The Mountain is like 'standing a foot and a half above most men in the camp', the average height in 2022 for men is 5'9'', so The Mountain is like 7'5''. Close to 8' and close to Edmund's deduction of 'Eight-foot tall'. How might I forget Ahriman's own words of (i'm paraphrasing rn) "we ought to recycle more Ignis", the newest recruit of the Kingsguard may be one we have actually seen.
On the other hand why does Aeyron elicit Ahriman to do this. Aeyron lets him murder innocents and experiment on them, but why? Well get your conspiracy hats on because this is wild. Aeyron is distraught with guilt about Joanna. He has fallen into a deeply depressive state without her by his side. Joanna is dead...but is she? What if Aeyron could bring her back to life? What if Aeyron has employed Ahriman to bring The Mountain abck to life as a test; if he can do that then he can bring back Joanna. Why else would Aeyron employ Ahriman? There actually may be some sort of evidence for this in the books, atleast of some people coming back resurrected.
Where is Joanna buried? Well we can assume she and Domeric Forrester were taken back to WinterFort by their father, so there is a possibility that they could be buried at the crypts of WinterFort. And if they are buried in the crypts of WinterFort then things can get spicy. The crypts are described as 'housing the dead of the Forresters locking them away so their vengeful spirits so they would not go wandering about the castle', but Gerold Forrester remarks 'Many of the swords were rusted away into nothing so did that mean the spirits were free to roam around the castle?'. If the Forresters's spirits are let loose then they are not chained away; and so this might be the case for Joanna. Joanna did not fight, she has no sword. I don't imagine she was put in her tomb with her statue holding a sword, Joanna's spirit is thus free. This may be a clue which tells us that Joanna is no longer trapped in the statue of death, and that she will be resurrected by Aeyron and Ahriman.
What do you think? Pretty out there don't you think?