Dimidue had potential. It Could have been a great ship that made me feel all the feelings, but it sort of goes with my criticisms on now Dedue's character is handled in general. I love him, but I wish they'd given him an arc that allowed him to grow past the 'everything for my lord' thing, specifically because his trauma intersects with his race. He experiences systemic racial violence, so I find his dynamic with Dima a little uncomfy; but thankfully so does Dima, so at least someone's aware.
Yeah, I'm not too happy about Dedue's complete devotion to Dimitri either but at least people mention how unhealthy it is on occasion, not least of all Dimitri himself and, in his own inimitable way, Felix
I think what the intend was to contrast Petra's kinda forced devotion to the Empire. She has no choice but to follow to keep her home safe but does potentially decide to fight back, Dedue chooses to follow out of hope for a better future for his people and kinda loses sight of where loyalty ends and obsession begins...
It's not as well done as other things in the game, like Claude's arc or as I said Petra's moral struggle, but hey, you can't win em all