The history of this incarnation of Franklin Richards most likely mirrors that of his earth-616 counterpart, up until the moment that his mother got pregnant again with her second child.
The child however turned out to be a monster: a succubus who drained the life energy of others. It already began while she was still an unborn baby in her mother's womb. Over time, Sue’s pregnancy took a horrible toll on her. She got weaker by the day and almost skeletal, soon losing her invisibility powers. When she gave birth to her child, she died in the process. Reed named the baby Sue in order to deal with the loss of his wife.
As the years go by, only Franklin Richards realized what a monster his sister really was. He never allowed himself to be near her. When Sue was about three, Franklin noticed that their babysitter Alicia Masters was being affected in the same way that Sue was. She soon died as well. Johnny was next to go. Franklin tried to warn his father about it, but Reed refused to see reason. Susan's next victim was Ben Grimm, who lost his powers and was happy about it. One night out on the town, he came across a mobster he once clobbered who wanted revenge. Ben got shot up and ended up in the hospital. Even though it was possible that he could pull through, it was all for naught when Little Sue visited him with glowing red eyes.
Finally, Franklin took a trip to Latveria and got an audience with Doctor Doom. Going over the evidence, the two decided that Susan was a succubus of some sort. Doom had interest in this since with her growing power rate, she could one day be a threat to Latveria. When they returned to the Baxter Building, Reed blocked their path, having gone completely mad under Susan's influence. Doom, seeing that Reed was beyond reasoning, knocked him out. Right then, Susan finally revealed that Franklin was right by assuming her true, monstrous form. Reed apologized to Franklin for not believing him before being devoured by Susan. With Reed gone, Doom fought Susan to buy Franklin time to get away. The fight didn’t last all too long when Susan could absorb the energy running Doom’s armor. Doom’s life force was eaten away, and Susan continues to hunt Franklin. She found him waiting with a large cannon. She laughed at how he expects to kill her with a mere gun, but it was only a ruse. He was only using the gun to blast her back into a portal to the Negative Zone that birthed her. Franklin then destroyed the portal so that she could never make it back. Within the moment, Sue already found herself in a showdown with Annihilus.
Now all alone in the Baxter Building, Franklin lamented how none of this would have happened if his father had just listened to him.