10 MCU Loose Ends That Will Mean Something In Phase 4

1. The Red Room Programme

What we know about Black Widow's mysterious past can probably just about cover a single page of that ledger she used to mention. We now know the name of her father, Ivan, thanks to Red Skull; We know that she was a product of the Red Room; We know SOMETHING happened in Budapest; And we know that she defected to join SHIELD. That's not really a broad enough picture to explain why a psychologically conditioned agent of murder suddenly decided to up-sticks and join the other side.

Even more intriguingly, the flashbacks in Avengers: Age Of Ultron confirmed that Natasha wasn't the only Black Widow and from then on we could only imagine where the others went. Thankfully, we need wonder no more as the Black Widow solo movie is going to introduce us to at least TWO other Black Widows and also Red Guardian, who appears to have been a product of a similar programme - probably the same one that created The Winter Soldier.

Black Widow is likely to close out the Red Room story as some of its most famous graduates turn on it, but before that happens, we should hopefully get more answers about it and Natasha's veiled past.