Idea's from Marvel Avengers Assemble and Marvel Earth's Mightiest Heroes, The Avengers and Marvel Future Avengers

Here a Thor idea

What if Enchantress took Thor to a realm she made herself and she slowly started a brainwashing process that will make Thor forget everything and everyone, she also planted false memories of her and Thor being rulers of that realm and being husband and wife. Will Thor ever regain his memories and will his friends and teammates find him.

Here is an Hawkeye idea from the episode of the Circus of Crime

What if the Ringmaster was planning on having Clint Barton AKA Hawkeye back to his real family, he finds a hypnotist that will make him forget the Avengers, Ringmaster was also planning to do a experiment on him that will make him have a change of personality and make sure that Hawkeye will only believe what he want him to believe. Will the Avengers find and save him.

Here a Iron Man

What if one of Tony's experiments went wrong and it turned him into a baby or a 5 year old with no memory of The Avengers or anyone. So what will happen when the bad guys get him and decide to turn him against the Avenger or just brainwash him ? Will the Avengers find Tony and turn him back to normal ?

Here is another Hawkeye idea

What if the Ringmaster decided that he will turn Clint Aka Hawkeye back into a child and re-raise him to hate the Avenger, but to also make him believe that the circus of crime is his true family. When the Avenger somehow gets him back he doesn't remember them at all, will they find a way to turn him back to normal and how will they look after a child Hawkeye ?

Here is another Iron Man idea

What if a woman from his past comes back and she kidnaps Tony and takes him to a secret place. ( I found this old series on Disney plus, the episode is called Beauty Knows No Pain) the woman is called Whitney who is slowly brainwashing Tony to make him forget that he is Iron Man and the Avengers, she is also having some false memories being planted in him as well. Will the Avengers find and save him ?

This idea is from an episode not my so if you don't know it, try to watch it or read it from wiki

Here is another Hawkeye idea

What if Ringmaster adopted Clint when he was a toddler, he along with the other members raised him. But Clint was taken by some mystery people or by someone who wanted revenge on Ringmaster for something, when they have Clint they started an experiment on him with some other kidnapped children. The experiment is to make the person forget who they are but keep their personality and skills, but suddenly S.H.I.E.L.D comes to rescue the children and put an end to the experiment. That when one of the shield agents recognises Clint who is unconscious after the experiment as Trickshot from the circus of Crime. S.H.I.E.L.D decided to take him back with them and talk with Nick Fury of what to do with him, after a while S.H.I.E.L.D made a decision on raising the Amnesia Clint as a shield agent before becoming Hawkeye and part of the Avenger, meanwhile the Circus of Crime been watching and waiting a chance to get him back. When they hear that S.H.I.E.L.D send him on a mission they made a plan to capture him, they also met someone to help them with making sure that Clint have no memory of shield or the Avenger, they also plan some fake memories for him during his brainwashing process when he is brought here. After some days have passed the process was finished and a new Clint was born, meanwhile the avenger and shied been searching for Hawkeye when Black Widow or the others Avenger was called on a mission where the Circus of Crime is. When they got there they were shocked to see Hawkeye, Natasha said Clint is that you ? In a shocked voice but Clint just stared at her and the other Avengers then said how do you know my name. Then Ringmaster has someone do a distraction to escape with what they got, when they return back to Avenger tower they contact Nick Fury to ask him about the Circus of crime after telling him what happened to Hawkeye. That's when Fury reveals to them about Hawkeye's past. Will the Avenger save and bring back the old Hawkeye they all now ?

Here is another Hawkeye idea

What if Hawkeye got into a fight with someone at Avenger Tower ? Natasha got herself involved but only made it worse, then Natasha said something very hurtful to Clint. Everyone stares at her in shock, Clint looks at her in anger and shock. Widow try to apologize but Clint said he was going out, meanwhile the Circus of Crime was watching and waiting to capture Hawkeye. Ringmaster was met by a witch queen who wanted a son, the Witch queen explains to Ringmaster and the others members why she wanted Clint Barton aka Hawkeye to be her son, so when the Circus of Crime returns with Hawkeye who is unconscious, the Witch queen was please and completed her side of the deal. (You can choose what kind of deal Ringmaster made with her is) Clint was then put into something during the trip back to the Witch queen kingdom. The Witch queen gives something to Ringmaster so they can contact each other when needed to, the Witch queen explains how and what she will use to turn the soon to be former avenger into a child, then use something to slowly make him forget his old life, but she want the circus of Crime to teach and train him so that he have some skill and stuff. Meanwhile it has been over two months and a week when Hawkeye left after the fight, Widow and the other avengers have been searching for him ever since. Widow regretted ever saying those words to him and will do anything to make it up to him. During a mission the Avenger saw the Circus of Crime and a young child that looked similar to Hawkeye, Widow sneaked quietly to hear and have a closer look at the child, Natasha used a special device to let the other Avengers know what was happening. But when Natasha saw the child's face she knew it was Hawkeye, but at that time one of the members saw her, they made their escape while fighting the Avengers. Why they were fighting Ringmaster took the Child Clint and contacted the Witch queen to get him, but unknown to them Widow and Thor was secretly following them and saw Clint going to a strange woman. Before either Avenger can do anything the Witch queen sees them and uses her magic to blast them. When they got back up they were already gone, the other Avengers came and asked what happened, Thor and Widow explained to them what they saw. When they got back to Avenger tower they made a plan on how to bring Hawkeye back home and to his rightful age.

I will let you decide the rest, will the Avengers save Clint ? How will Natasha show how sorry she was for what she has said to him.