Why did Hank Pym beat Jan? Was he drunk? Did she say or do something that made him flip off? Have they ever tried to retcon this? How did his teammates react to him?
In the original storyline (pre-retcons) Pym was experimenting with a growth chemicals that accidentally induced schizophrenia in him which created a split personality (Yellowjacket).
Hank Pym has his first mental breakdown when his first wife maria in murdered on their honeymoon. Pym has to identity for her body and loose it running around Budapest trying to capture her killer.
In AVENGERS #59 (1969). Hank Pym is conspicuously missing from the Avengers meeting, and then Yellowjacket shows up, claiming to have killed him. Yellowjacket is a crazy cocky, dangerous loon without any of Hanks impulse control.
In AVENGERS #161, by Jim Shooter and George Perez. In this story, Hank gets most of his memory wiped out by Ultron (an evil robot that he created), and so doesn't recognize any of his teammates and attacks them.
In AVENGERS #212, by Jim Shooter and Bob Hall, published in 1981. The Avengers have to head off to face a new villain named the Elfqueen, when Hank gets a unprovoked shot at the Elfqueen leads to him being court-martialed, with his Avengers membership getting put into question.
The court martial drives Hank over the edge. He's so driven to keep his Avengers membership that he comes up with the worst possible way to keep it. He creates a robot named Salvation I (Sal for short) to attack the Avengers during the court martial, so he can save them by blasting it in its vulnerable spot, which he, of course, designed.
Pym has lost it and when Wasp tells him not to do it, that's when he slaps her.
Jim Shooter wrote the scene in which Hank is supposed to have accidentally struck Janet while throwing his hands up in despair and frustration—making a sort of “get away from me” gesture while not looking at her. Bob Hall, who had been taught by John Buscema to always go for the most extreme action, turned that into a right cross! There was no time to have it redrawn.
In the court martial Pym as Yellowjacket who has by now gone on a full mental breakdown says Captain America is only angry because he had the hots for the Elfqueen and has a vendetta against.
The very next issue, Pym tries to talk to Janet and acknowledges that he needs help. When Janet says she won't put up with him anymore and wants a divorce, Hank leaves leaves.
Things went even more downhill for Hank after this. He got manipulated by his old enemy Egghead into committing a federal crime. He was put in jail. Tony Stark dated the Wasp while he was in jail.
On the day of his trial, Hank is kidnapped by Egghead, who believes that Hank is so far gone that he would be willing to join the Masters of Evil. Hank does, but then it turns out he's just playing along so he can build a machine that will let him beat down the Masters single handedly.
After this, he punches out Egghead, who pulls a gun at him. Hawkeye arrives just in time to shoot an arrow into it, which kills Egghead, but there's enough evidence in Egghead's lair to clear Hank.
The storyline comes to a close with Hank forgiving himself and living with what he did. Since Egghead manipulated Hank, the Avengers are willing to give him the benefit of the doubt and ask him to go through a mental scan to see if his actions were caused by an outside influence. After he takes it, Hank gives off saying "I made my own mistakes, and I have to live with them."
The Avengers have to hold a court martial for Hawkeye after he accidentally killed Egghead saving Pym's life. It's just a formality, but Hank steps up to defend him. The Avengers acquit Hawkeye, they go to apologize to Hank for not doing more to help him. Again, Pym takes responsibility for what he's done. Pym also apologizes to Janet again and make peace with each other going their separate ways.
Pym tries to commit suicide putting a gun to his head before he is stopped. He goes on to join the West Coast Avengers, first as a consultant, then as a nonpowered operative. Eventually, he'd become Giant-Man again and rejoin the main Avengers team and eventually, he and Jan fell in love again and started dating.
The storyline was pretty much resolved and wrapped up over 30 years ago but writers constantly almost go back to it. Pym spent the last 30 years crying over slapping Janet and being backhanded by numerous women in revenge.
There have been numerous retcons going into more detail about both Pym's mental state and Janet turning a blind eye to he mental problems over the subsequent years. Hank Pym in the latest issue of Avengers AI was diagnosed as Bipolar.
In the Ultimate comics in which everyone is a ass**** instead of Pym slapping Janet once in a mental breakdown Pym regularly beat Janet for years.
Which is probably where people who have not read the original 616 story (It is 30 years old) got the idea that Pym is a violent wife beater.
Peter Parker once backhanded his pregnant wife MJ across the room into a wall as well but Spider-Man draws more dollar bills than Ant-Man/Giant-Man/Goliath/Yellowjacket so they One More Day it (act like it never happened
)
It is kind of funny that in Spider-Man 3 Peter also hits MJ so perhaps someone at Sony totally remembers that issue
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