But in the Ultimate Universe ( Which the movies have taken a lot of Ideas from) Cloak & Dagger got their powers by Having Dark Matter tested on them. Besides in 616 I think it was a cheap substitute for heroin Or some other kind of alternative.

Look at Bruce David Banner from the Incredible Hulk television show. Previously, the Hulk's origin had involved him being exposed to the radiation of a nuclear bomb after deciding to run into the bomb's test zone and rescue a teenage boy who stupidly drove into it as part of a dare, but the series decided to make Banner exposed to gamma radiation as part of a deliberate science experiment that went wrong and mutated him, and adaptations seem to have used variations on that second origin ever since. Cloak and Dagger could easily just revise their origins for the screen, since "one has beams of light, and another can pass through solid objects" could come from more or less anything as far as comic origins are concerned.

Honest question here: what would a Black Widow movie be about? I can see the potential story paths of a Carol Danvers movie, or a Kamala Khan movie(though I think the latter may be too recently introduced to get an adaptation for a while yet), but I'm not sure what would drive the plot of a Black Widow movie. Maybe the mysterious past mentioned in Winter Soldier could bring up some sort of threatening force that sees some use in her and/or wants to kill her, but that seems awfully generic. Maybe the movie could follow her on a mission to the remnants of a facility destroyed/abandoned/made unfit for human habitation by what her new information reveals to be AIM or HYDRA efforts, and then she'd have to outwit a new baddie or group of baddies that was lying in wait ever since the events that led the base to be cast into disuse base awakened them/reactivated them/unwittingly became their origin story, but that's only a few degrees better. I don't know much about the Black Widow's background in the comics, which is part of why I need to ask the question in the first place, but from what I've seen in the movies, she seems to work best as part of a larger cast, where she can be the Badass Normal to offset the more larger-than-life figure of a more traditionally superpowered character and show that both sides are equally competent and effective in their own ways, and yet if one of the other Avengers tagged along with her, it would take the focus off of Black Widow as the lead, and would make it more likely that the threat faced in her movie is one of the tagalong's enemies instead of a Black Widow/SHIELD-specific enemy, further minimalizing her, and no one wants that.

To re-ask the original question, what would/could/should the plot of a Black Widow movie be? I'm genuinely interested, but I just can't think of anything good right now. Anyone have any thoughts? Preferably ones that use fewer forward-slashes than I just did?