That was something that was always in there. It was a Shuri thing, because you know in our world we kind of figured that Bucky Barnes would be her assignment. We kind of drop the hint at that when they bring Ross in and she's like, 'Oh another one.' So, we dropped hints in there, but the idea for that, what we kind of decided, we decided was that her cracking his mental code, if Shuri's as smart as she is, that wouldn't really be a big problem. But Bucky would have horrible PTSD, he would need spiritual guidance.
With
Black Panther being the last Marvel movie before
Avengers; Infinity War, many of us expected this movie to set the stage for the big team up with lots of references and set-up, and with the end of
Captain America: Civil War showing us that the Winter Soldier was in Wakanda, he seemed like the most obvious Marvel character to appear. The main film, however, only makes a passing reference to him as a "broken white boy" but in the closing credits, we see Bucky Barnes with
Shuri, having been apparently successfully rehabilitated.