Unalaq and Vaatu maybe relations theories

I have already wrote my suspicions and theories in my previous post about it, there is some other theories around the fandom that maybe Vaatu wants to connect with a human because he sees how powerful and huge potential it becomes through how Raava and Wan fused forming the avatar entity, he wants to use Unalaq for that purpose, probably and Unalaq wanting it too...
I have to disagree with most points of the theory, I doubt about Unalaq wanting an kind of Dark Avatar entity, because something isn't fitting here, there is some holes in the theory, such as Unalaq got irritated with his son and daughter for not getting the avatar, when he come out of the spirit world in hurried way, when Eska said "the avatar is dead", it changed to a worried expression, you can tell he is in a hurry of something and one more thing, if Vaatu would be so interested in doing so, wouldn't have he done it by now? I say this because there is Dark Spirits and they are "out of control", the one who turns spirits into dark spirits is Vaatu, we can assume he is free to some extent and someone released so he could perfectly already turned Unalaq into Dark Avatar, it may be his intention somehow and is tricking him, also why would Unalaq being able and doing exact opposite of Vaatu with the Dark Spirits...

Another details I want you to look at:

If you notice how they vanish when turned into light spirits and when Ravaa and Wan fused (being their spirits fused and bonded together) vanish, it's very similar, the swirls around dark spirits turned into light spirits is kinda similar to the statue of Avatar Wan with Raava, specially when it shines, there is still things left to explain, I think this happens when they lose their physical presence (not a physical body but presence) and reborn or come back in a different form.
That's one of the reasons I think just doesn't fit regarding Unalaq being power-hungry, I think is something that has gone wrong related with what Unalaq did in the past...
there is questions I'm sure it will be answered, remember close to the conclusion of the backstory of Avatar Wan, he said to Vaatu:
 "This is your prison now. And I will close the portal so no human will ever be able to physically enter the spirit world and release you."
remember he said so no human can physically enter the spirit world and release him, in another words you can only enter from then on spiritually, that's must be why Avatar Wan could bend there because he was physically&spiritually there, of course, so how Vaatu is getting to affect spirits turning into dark spirits? it's possible maybe someone have entered the spirit world spiritually (not physically) and must have released him  to some extent, my bet is Unalaq, tricked him, maybe is still doing so (for Unalaq wanting Korra to open the portal or something else, could be as double agent), so if he is released completely, Vaatu will probably want to take chance to use Unalaq to be an Dark Avatar.
I still stick with my theory and mix some with the other theories about the "Vaatu- Dark Avatar" and waiting for the right moment...