With Namor's impending debut in Black Panther: Wakanda Forever, fans who are eager to read about the Atlantean's uneasy relationship with T'Challa need look no further than Jonathan Hickman's New Avengers run. The upcoming movie will inevitably take some cues from New Avengers, considering the scenes which Black Panther and Namor shared together were a clear highlight of the series.
Before Hickman began writing New Avengers, Avengers vs X-Men sparked the rivalry between the two kings. Corrupted by the immense power of the Phoenix force, Namor flooded Wakanda, causing untold damage. After an extended battle, the combined force of the Avengers was just about enough to defeat Namor. Yet even though the Phoenix's energy had left Namor, divisions between him and Black Panther were left unresolved. The tension between the two of them only escalated when the Illuminati reformed following a looming threat to the entire multiverse.
This quickly became apparent in New Avengers #2, with neither Black Panther nor Namor making any effort to conceal their dislike of each other. In a scene with just these two characters, Namor teased Black Panther that he had to call on the Illuminati for help after previously refusing to take part in the group's covert operations. In turn, T'Challa vowed to kill Namor once the multiversal crisis had been dealt with, citing his actions during Avengers vs X-Men. Hickman did an effective job reflecting the antagonistic relationship between both of these characters in this scene, and therefore set a tone for their interactions going forward with New Avengers.
As the series progressed, Hickman explored the mounting political tension between Wakanda and Atlantis. T'Challa tried to dissuade Shuri as Queen of Wakanda from waging war, hoping to prevent a diversion from the bigger issue at hand -- the gradual destruction of the multiverse. However the plea fell on deaf ears, with Shuri dead set on revenge. So when Namor returned back to Atlantis, he was distraught upon finding his home in ruins, and his people brutally slaughtered. This startling plot development not only stoked the fires between the two kingdoms, but would also have disastrous consequences throughout the rest of the series.
Hickman revealed these dire ramifications in a tie-in to the Infinity event, when Thanos' army came to Atlantis in pursuit of the time gem. Filled with a thirst for vengeance, Namor purposefully misled Thanos' army to Wakanda. So while T'Challa was off-world, the Mad Titan's forces broke through Wakanda's defences, taking the lives of several Wakandan soldiers and finding Black Panther's secret hideout, which was filled with deadly weapons. T'Challa's absence from the battle proved costly, seeding so much doubt among the rest of the Wakandans that he was cast out from the kingdom. As a result, Hickman was able to cleverly illustrate how Namor's deceit triggered an entire chain of consequences which adversely impacted both Wakanda and T'Challa himself.
New Avengers #17 had a nice moment between T'Challa and Namor, where they're having a reasonably civil conversation about their differing philosophies. Contrasting Black Panther's optimism, Namor was depicted as a deeply nihilistic character, blatantly rejecting any notion of morality, and upholding the end of existence as the only thing of any real significance. Yet in spite of their differences, the two of them were still able to drink together and even share in a moment of laughter. This just goes to show how much thought and consideration Hickman put into T'Challa and Namor's character interactions, with their relationship feeling incredibly nuanced and grounded in reality.
Unfortunately, Black Panther and Sub-Mariner's peace was to be short-lived, when the Illuminati were presented with a huge moral conundrum-- should they kill the entire population of a parallel Earth to save their own world? While T'Challa couldn't bring himself to destroy the planet, Namor was able to do so without hesitation. Disgusted by Namor's unflinching brutality, T'Challa attacked him, resulting in an intense fight, where all their anger bubbling away under the surface for so long had finally erupted in a big way. Hickman fully tapped into the dramatic potential of this brawl by having Namor angrily confess that he was the one who directed Thanos' troops to Wakanda, which only aggravated T'Challa even more. This brilliantly executed scene was filled with so much emotional weight, that it remains one of highpoints of Hickman's entire Avengers run.
Following this, Hickman delivered the ultimate payoff to T'Challa and Namor's long-standing feud in in the "Time Runs Out" story arc. Black Panther attempted to make good on his promise to kill Namor all the way back in New Avengers #2, stabbing him, and overseeing his fall back down to a parallel Earth just about to explode. Yet given Namor's extraordinary superhuman physiology, Black Panther was all too aware that his foe would survive the fall, so purposefully waited for a few moments to allow Namor to properly process T'Challa's final act of revenge, while reeling from the damage he had sustained. It was an earned character in that it showed that Black Panther and Namor's relationship had finally reached its breaking point.
Though Hickman was not finished with T'Challa and Namor just yet, as they reunited in Secret Wars, the epic culmination of Hickman's time on the Avengers. The iconic pairing both managed to survive the end of the multiverse, finding themselves in Doctor Doom's newly created reality, a world where he ruled with an iron fist. Consequently, T'Challa and Namor had to put aside their troubled history with each other if they were to find a way of overthrowing the sinister regime. Hickman clearly had a blast writing for these characters once again, as Black Panther wielded the Infinity Gauntlet and along with Namor, led an army of zombies into battle against Doctor Doom and his followers. Secret Wars proved to be fun in part because of the Black Panther and Namor team-up in Hickman's final Avengers story.
Taking everything into account, Hickman's Avengers run made a highly convincing case for why T'Challa and Namor have one of the most fascinating, complex relationships in all of Marvel's history. Hopefully going forward, Black Panther: Wakanda Forever and other MCU projects can incorporate elements of this shifting dynamic, to encourage more readers to check out this spectacular set of stories.