Whoever you'll see in the mirror, your memories will be changed so you think you're in love with that person. I think Osiris meant for Seth to look into the mirror, but nephthys accidentally picked it up? This is why Horus is reluctant to help the nephthys in the mirror dimension get out because Seth still loves her
When horus looked into the mirror, nothing changed because he saw Seth and he was already in love with Seth
The mirror was planted by Osiris.
He started the war with the Sun god because he wanted the bronze mirror for it's power.
The mirror makes anyone who looks at it fall in love with the person they see. Osiris made the mirror show his image, so the next person that looks at it would fall in love with him. He knew Seth would take it, but he didn't count on Seth not looking at the mirror. So his wife looked instead, and she fell in love with Osiris.
Now Horus explained that since Seth's wife didn't love Osiris, her consciousness was split into two. One that is the original (that loved Seth and not Osiris) and one that the mirror made so it loved Osiris.
I don't remember well but it seems that in first season Bestet (if that is her name) made Horus look at the mirror that had Seth's image. But because Horus already loved Seth nothing happened to him, his consciousness wasn't split
The thing we still don't know, but (heres my theory) it's how you can make a specific person to appear in the mirror.
If we look closely, the back of the mirror has an engrave of two godesses (one is sekhmeth, godess of chaos and the other one I assume is sun godess) both of them are holding a mirror, so we can assume that actually there are TWO mirrors.
When you look on one of them, that's the image that the other mirror would reflect later, to anyone who looks at it first.
My theory is that the one Osiris took was the sun godess's one, the other one was in Sekhmeths's possession OR Osiris had both but the only one who can activate them is Sekhmeth, because if we look close to what they said, Nephtyss asked "oh, it only works at night?" because in the day neither Seth or Nephtyss could see anything.
And later when Isis told Sekhmeth it was all her fault. She said "Osiris is the one at fault, I only PREVENTED him to succeed on what he wanted", she was implying he wanted Seth to be the one to look his image in the mirror. But maybe Sekhmeth decided to activate it when Nephtyss took a look alone (she loves to spread chaos too and probably hates Osiris, so it makes sense).
Finally if I remember correctly, the time Horus assaulted Seth, the one who incited him looking in the mirror was Sekhmeth (I will reread this part, maybe im hallucinating)
So maybe she was the one who implanted Seth image on the mirror or the one that activated for Horus to look at it. I think a part is missing there.
Just to add to your theory (it's spot on btw), Sekhmet didn't implant Seth's image, if u remember back in S1 Hathor had the other mirror and she was planning on using/activating it cause she knew that Horus had the other mirror, but Seth got in the way (Smth about him wondering why she smiling like that idek), anyways, then he snatched the mirror and the exact time he snatched the mirror that's when Horus also looked into the mirror he had....aannddd saw Seth( ̄∇ ̄")
This is also when we found out that Hathor can use a fire ability which is characteristic to Sekhmet(〜 ̄△ ̄)〜
OH I DIDN'T REMEMBER THAT! THANK YOU!
That totally makes sense now, I didn't remember if Seth had a chance to look at it. But now that we know that. We can confirm there are two mirrors and that Sekhmet is directly involved on how they work.
I want to add that they appear to have an aphrodisiatic effect too. Thats why Nephtys had that yellow eyes and asked Osiris to make a baby with her (despite her wish, that was Osiris help her to make her conceive with Seth, not for literally making a baby with him for Seth xd), and the time Horus attacked Seth too, it was clear that he hadn't have control over himself.
Guys I just re-read those episodes and everything connects perfectly. When Seth choped Sekhmet's arm, she was very angry. She was the one who implant the idea on Seth to go to Horus bed.
And when Horus was still in his bed, waiting for Seth to do what he wanted.
We see speech bubles that are of Sekhmet, at the same time we see the engravement in the mirror where the image, we confirm it's her, and she says "you did this all by yourself Seth, I hope you don't get angry, I told you what to do, but you could just not do it, you knew you would regret doing this to Horus, but you are going to do it anyway" or smth like that.
And then, the "BOOM" and "TING" sfx, Seth and Horus got disoriented and then WE CAN SEE HORUS EYES TURNING YELLOW-CAT PUPILS JUST LIKE NEPHTYS WHEN SHE BEGGED OSIRIS TO FUCK.
So we can confirm, Horus was being controlled and it's still a good boy
can someone explain the mirror shit to me please Im kinda confused?? also, fuck Isis