WARNING: The following contains spoilers for Fantastic Four #33 by Dan Slott, R.B. Silva, Luca Maresca, Jesus Aburtov & VC's Joe Caramagna, on sale now.
In an uncharacteristically kind move, Doctor Doom cordially invited the Fantastic Four to his wedding to Victorious. He also invited Black Panther and Namor, and he promised everyone attending a clean slate, with all past sins and perceived slights forgiven.
While this was a matter of diplomatic importance for monarchs like Black Panther and Namor, the Fantastic Four were there for their own distinct reasons after Doom asked Mister Fantastic to be his best man. Moreover, Reed Richards said that Doom promised to forgive all who attended for their past transgressions if they attended his wedding to Victorious. He admitted that a clean slate with Doctor Doom was too good to pass up. That is when every member of the Fantastic Four -- except the one who needs forgiveness the most -- admitted to something from the past that could use wiped clean.
Reed Richards
Reed Richards likely has the most conflict with Doctor Doom to clear up. As two of the smartest men on Earth, Reed and Doom have a deep rivalry that's only occasionally allowed them to acknowledge each other with any respect beyond professional courtesy. Doom's invitation came through Reed, and the two had a duel for this honor in the last issue, with Reed losing and forced to accept the role of Victor's best man for his wedding.
Since Doctor Doom's debut in Stan Lee, Jack Kirby and Joe Sinnott's Fantastic Four #5, the entire feud between Doctor Doom and the Fantastic Four is rooted in the rivalry between these two geniuses, and ending that feud could help the Fantastic Four in more ways than one.
The Thing
The Thing admitted he had one big mishap in the past that he could use wiped off the record. As Ben said, he feels directly responsible for the injuries to Doom's face, which go back to the beginning of Doom’s hatred of the Fantastic Four. Doom was a brilliant student who always tried to mix forbidden magic with science, but he ended up expelled from university when a scientific experiment exploded and scarred his face.
The machine Doom was working on was a way to free his dead mother from Mephisto’s hold. He blamed Reed for the accident for years. In 2013's Fantastic Four #9 by Matt Fraction, Mark Bagley, Mark Farmer, Paul Mounts, Guru eFX and VC’s Clayton Cowles, that all changed. According to that issue, Ben Grimm messed up Doom’s research and was actually responsible for the explosion and the scarring of Doom’s face.
Invisible Woman
Earlier this year in Fantastic Four #28 by Dan Slott, R.B. Silva, Jesus Aburtov & VC's Joe Caramagna, the Griever at the End of All Things showed each member of the Fantastic Four how they would die. The Invisible Woman faced an especially grim fate. Doctor Doom had murdered the other three members of the team years in the future, but he saved an older Sue Richards for last. He then explained to her why he had saved her death for the end.
Confronting the Invisible Woman, Doom admitted that after 60 years, he still hated her the most, adding that she committed the unforgivable sin of unmasking him in front of the whole world. When the team considered whether or not to attend Doctor Doom’s wedding, Sue reminded the team of that grudge and said she had to go to help the team avoid that grim future, even if she and Doom didn't have any specific grievances from the past.
Human Torch
Ironically, Doctor Doom and the FF went into this wedding under the impression that the villain didn't have any grudges against the Human Torch. Johnny Storm was present for every battle with Doom, but he had done nothing that could have caused a grudge big enough to one day doom the Fantastic Four. Still, Johnny went to the wedding anyway, hoping to get a 'get-out-of-jail-free card' from Doom. However, he will never get that, thanks to his indiscretions before the nuptials.
The Human Torch slept with Doom’s future bride right before he proposed, and that was enough for Victor to retract his promise and attempt to kill everyone in attendance at that moment. While Johnny Storm didn't have a grudge with Doom for decades, some extraordinarily bad timing and his poor choices have ruined the FF's best chance to patch things up with Doom for the foreseeable future.