Steve starts of as an omega but because of the serum he changes into an alpha.
While Bucky on the other hand starts off as a beta and thanks to HYDRA's experiments he becomes an alpha as well.
I think it was set in the 1940's to start with, then 70 or so year later in the future.
I can't remember much else except for Tony maybe being an arse.
Please if anyone knows what this fic is called I thank you in advance.
(Also please don't let it just be in my head).