Rick Remender's utterly abyssmal treatment of Captain Britain on Secret Avengers (and his Uncanny X-Force run before it).
Through Secret Invasion and Dark Reign Brian Braddock was a headliner of his own series. He was a poster boy for 'The Heroic Age', being given a variant cover for Age of Heroes #1 (In which Steve Rogers invited him to become an Avenger like 2 years before he actually debuted). He had long since been shown as a fully developed and responsible leader, with ties to Spider-man, The Black Knight, the X-Men, Captain America. At no point were these negative associations. Far from it. At that point he was a well-rounded character, who after Captain Britain & MI13's run felt like he had finally been put right, after years of inconsistent usage. Clearer powerset (power levels now determined by personal confidence, but plausibly limitless), less complicated role (no more interdimensional adventures, just a guy protecting one Country), simpler costume (we actually got see a more human, more expressive face), greater recentered sense of purpose (working for the British government, sorting out supernatural and superhuman threats). He was all set for any new writer to pick up the character and run with him. Simple.
Here's his fact file from the 'The Heroic Age: Superheroes' handbook.
It's a rightfully pretty glowing report. It's a few years ago now, but even a fair number of neutral fans were interested to see his inclusion on The Avengers.
And then it didn't happen. The rosters were slowly revealed for the Avengers titles and Captain Britain was not on any of them. Confusing as hell to readers, but that's how it happened. With each new roster change on each Avengers title the question would get raised, when would Captain Britain be showing up? So when Rick Remender finally announced Brian would be on his Secret Avengers roster a lot of people were kinda psyched about that. In interviews it genuinely seemed like Remender was enthusiastic about including the character, and seemed to be a bit of a fan. Which is ultimately why the end result of the character we saw in print was so utterly bizarre.
Read back over that character profile. That's the Brian we expected to see. The Brian Braddock that Marvel comics wanted to show. That is the image of Captain Britain that was fresh in people's minds before Secret Avengers and Uncanny X-Force. One of a man of great humility, courage and decency. But a guy who would NEVER boast or brag about such things. To coin the phrase from Brian himself, upon facing off against the Skrull 'Sorcerer Supreme' he may be all these things but he doesn't '...Make a Fuss'.
Look back at it, because that is absolutely not the character Rick Remender chose to deliver. The first, and more obvious, examples would be to undo a lot of the positive changes which had been made in Brian's previous series. The new costume dumped for the old. A return to confusing mulitversal universe jumping adventures. No longer working with the British government. All undone (though thankfully partly redressed since).
Through first Uncanny X-Force and continuing in Secret Avengers readers were treated to the following bizarre and inconsistent actions:
Brian demand not only the death of Fantomex, but his complete erasing from all history and reality - without listening to any kind of explanation of the reason for his actions either second hand or from the man himself.
Brian actively bullying his sister, unrelentingly, into towing some kind of sense of a bizarre (and alarmingly brutal) 'Family Line,' which has simply never existed in any part of past continuity. Remender also appeared to believe that Captain Britain and Psylocke had long term intimiate knowledge of the father's life in Otherworld. As if they had always known about it. They had not.
They saw Brian regularly behave with an oddly uncharacteristically pompous and arrogant attitude. He was seen to actively brag about his many past roles and achievements in a manner which definitely does not fit with his trademark humility.
Brian showing contempt and disrespect toward the entire World War 2 generation, with sweeping generalisation that they are all '...sodding arrogant'. Apparently. You just don't do that. British people don't do that. Certainly not those of Brian's generation. This was just bizarre.
Brian being informed that no other heroes ever call upon him for aid because apparently everybody knows that he doesn't play well with others. Something which his past history of team-ups with the likes of Captain America, Spider-man, The Black Knight, Black Panther, The X-Men, Excalibur's teaming up with the West Coast avengers, his time working WITH Excalibur, or the Knights of Pendragon, or MI13 amongst others would seem to quite clearly contradict in droves. This is utterly illogical.
With each new issue it seemed to be another new element of an increasingly brutal and unwarranted character assassination. Brian was shown to be uncharacteristcally inept, unreliable, impetuous. It was nasty stuff.
I think it would be pretty clear to anybody reading that the intention here was probably to break the character down and build them back up again. But a) That was completely unneccessary, so close to his having been successfully reshaped and rebuilt, and b) The knock 'em down to build them up approach only works if you have a long run of stories in which to do that. Remender didn't. He only really had 3 complete stories on Secret Avengers, before moving on. It was never going to work.
Captain Britain as an Avenger is a total no brainer. But waiting two years for his debut, and the delivering this? That was a huge wasted opportunity.