I may be getting a bit over my head with this.
I just saw the Nate companion mod seen here and thought about what if Fallout 4 had the feature for you to build both Nate and Nora with different special stats. Not only that, but what if both characters were playable in a GTA V style kind of way where you can switch between them in VATS.
Players may give Nate a more powerful, tank-y build, while Nora has a more sneaky, charismatic build. For instance, in a fight scenario, you send Nate head-first into a group of raiders, while Nora sneaks around in the back to grab loot and get to the objective of the quest. This can also be Nora and Nate having the same Tank stats and being a tag-team of walking bulldozers.