This is an idea I had literally an hour ago at 6 in the morning, so bear with me but I thing its a great one.
The film stars Lou Diamond Phillips as Reed Richards, a former pupil of Howard Stark and a scientist trying to understand interdimensional travel, driven by the events of the avengers, more specifically the portal that appeared over new york and in london during thor the dark world. He's become a recluse driven by a dedication to his work to the point of losing all contact with former colleages, friends and his former spouse Susan Storm (Played by Rachel Weiss) (they're divorced by the start of the movie) and his son Johnathon Storm (played by Aaron Paul), a cocky military cadet who has a flair for showing off.
His only remaining friend is Ben Grimm (played by Bruce Willis in my dreams), a former Mechanical Engineer at Hammer Industries who, after being disgraced during the hammer incident at the stark expo, has been helping Reed with his work in hopes that he'll be able to regain some manner of respect in the scientific community and from his daugter (yes he has a daughter, preferably played by Rose Byrne, and she's a military test pilot) who see's him as ineffectual in his current state and thinks he needs to move on.
And of course the film wouldnt be complete without Dr. Victor Doom (Played by James Purefoy). He is in this version the ruler of Latveria, a country in eastern europe dealing with an influx of refugees from the neighboring sokovia after the events of avengers age of ultron. He's a former colleage and friend of Reed Richards who had a falling out decades ago, when a civil war broke out in latveria and Victor, revealed to be the last living heir to the latverian throne, chose his country men over his research and abandoning Richards to help his country. He comes to richards and offers to help him complete his research, saying he got his hands on the portal device from avengers, which was in shield custody.
He says that he found it in a hydra base his men attacked after the fall of hydra in AOU and wants to finish their work together. It's later revealed that he actually was in league with hydra while he fought in the latverian civil war and they helped him secure the throne. They were allies until the fall of HYDRA's heads when he betrayed them and wiped out the hydra forces within latveria, securing their weapons and technology, including a prototype armored suit intigrated with chitauri technology.
The biggest part of the movie I want to stress here is the relationship between Reed Richards and Susan Storm. They do not under any circumstances become a romatic pairing. Their relationship starts out at the divorce level, they fell in love, got marrried, had a kid and were torn apart by differing goals in life and Reeds obsession with the portal. Their relationship in the movie would progress past the disdain phase but would instead evolve into a non romantic co-operatiive relationship. They learn to tolerate each other for the sake of their relationship with their son.
Victor has a sliglt love interest that for the sake of the movie is only hinted at rather than outright stated in a character named morgan, a female advisor and right hand to doom who is implied by not explicitely stated to actually be morgan le fay, a love interest of doom from the comics.