Warning: spoilers for Daredevil #35!
As one of Marvel Comics’ most arrogant heroes, Iron Man has had so many disagreements with his fellow capes that he can be forgiven for forgetting a few minor clashes - but not his ruthless blackmailing of Daredevil. While Tony is notoriously difficult, Matt Murdock can be a pretty stubborn customer himself. Recently, however, they’ve managed to work together relatively well, with Iron Man even developing new weapons for Daredevil only to later give them to Elektra once she took on the mantle.
In Daredevil #35 by Chip Zdarsky, Stefano Landini, and Francesco Mobili, Elektra makes use of her brand new Stark-made sai, which provide sensory information on the surrounding area. She notes that Tony designed these weapons for Matt Murdock “without knowing he was blind.” This may seem like a throwaway line to explain how this tech gives Elektra similar abilities to Matt, but it signals an even bigger change to the dynamic between Daredevil and Iron Man. While Daredevil’s identity used to be public knowledge, Matt's double life was erased from public memory by the mind-controlling Purple Children, including Iron Man and his fellow heroes. And the fact that Tony no longer knows his secret changes their relationship entirely.
In Superior Iron Man #3 by Tom Taylor and Yildiray Cinar, a corrupted Iron Man - one who recently had his personality altered due to the events of the Axis event - goes head-to-head with Daredevil after Murdock takes issue with Stark releasing a highly addictive consumer version of the Extremis virus to the general public. When Daredevil threatens to bring Stark down, this more amoral Tony restores Matt’s sight in the hopes of getting Daredevil on his side by making him dependent on the product. While this story makes it clear that Stark knows Daredevil is blind, his gambit fails, and he eventually has to erase Matt’s memory of the conflict, leaving him with a lingering informational advantage over Daredevil.
With Tony’s memory of Matt’s identity so fully erased, the two heroes are finally back on an even playing field. Iron Man has redeemed himself since these dark days, and it's possible this short period was actually erased from history by the Secret Wars event, which saw reality destroyed and then recreated (though this possibility creates some plot holes of its own, as other comics have suggested post-Axis events remain in canon.)
However Matt and Tony's memories of this dark chapter in their relationship were removed, it marks a surprisingly rare occasion where a mainstream story effectively no longer happened for either of the heroes involved. While comics are prone to retconning the past to suit new narratives, it's generally through the context of time passing (like Captain America's anger over Civil War) or with the addition of new information (Scarlet Witch's House of M breakdown was later explained as being due to possession by the Life Force.)
Of course, if this conflict still occurred for other people and Iron Man has only forgotten thanks to the Purple Children, there’s plenty of storytelling potential there to be explored. After all, Iron Man isn’t the type who would be happy about someone playing with his memory, even if he started it. These days, Tony and Matt seem to be on pretty good terms. Stark will even be fighting alongside Murdock in Marvel Comics' upcoming Devil’s Reign event. But if Daredevil and Iron Man ever do remember their relationship’s darkest moment, it's likely there'll be hell to pay.