I will have spoilers, naturally
I think Will’s power is really that he is a blank slate. Which means that instead of him starting off with dark urges, chances he started off completely without any identity.
And he is resistant to letting anyone get close to him, so he cannot get any sort of self until Jack approaches him. When Jack approaches him, he starts working with the Garrett Jacob Hobbs case and I believe Garrett starts to imprint onto Will. His visions of Garrett are how Garrett is influencing him. Will’s first potential inprinter is maybe Alana, but she doesn’t. Then Hannibal sees Will’s power for what it is, beyond even what Jack can see, as Hannibal says Will is – A pure empath, and he can take the position of any person.
And then begins working with him, and also he is imprinting onto Will and for the first time, Will is letting someone do this. See Will is very against having a psychiatrist at the beginning. Cause he fights this.
I have also just found fish symbols in reference to Will. By being a fish symbolically, it says, everything around him is always influencing him. He lives in a watery unpredictable world. Will is often seen wearing blue. His passion is fishing. Water is a major symbol in the show. Then this quote about his house: “Will Graham, by comparison, dwells in a world described by association, meaning that similar colors and shapes create a continuous flow through his space, with many windows connecting to a natural setting. It’s a sensual fish tank in which everything is held in a kind of ether.”http://hannibal.wikia.com/wiki/Will_Graham%27s_house
So in short, I don’t think Will starts out dark now. Now I think it was imprinted. But as heard on why he is with Hannibal in season 3: When I’m with Hannibal, I know who I am.
Then again there are still the glasses issue at the beginning. But Hannibal says when analyzing Will, you are disturbed by the visions you cannot shut out.” (sorry none of these are direct quotes, but that is what I remember he is saying). So the glasses also I think are a way to keep people from coming into his space rather then just people seeing him. He is deflecting from being imprinted by anyone. But something about Hannibal makes him put his walls down.
Also in season 2, the way Will starts attacking Hannibal back after he’s released is using his blankness to get on Hannibal’s side by being the perfect pupil. Losing his own agenda. In SOTL it is explained that had Clarice come into Hannibal’s layer with an agenda he would have known. I would love to hear what you think. And also hear any opinions you have on it?