Call of Duty WWII
In the story, a young woman enlists solely because she needs to find her brother.
Brother has been experimented
Final boss is the brother attached to whatever monstrosity the Nazis created.

Timeskip(NON-LORE-WISE) to BO6
Story is about the guys from Cold War wanting revenge on Richtofen.
Once again, another young woman enlists in these nightmare because her brother was captured.
Once again, the brother was experimented on.
Once again, the brother becomes a monstrosity that has to be defeated.

It's the 2nd time this happens.I'm not complaining, just pointing out.

(Most likely someone else is aware of this)