User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-69.140.237.23-20111229175340/@comment-3062343-20111229215925

Bracchidios doesn't show up in any early quests, since it's exclusive to High/G-Rank. There may be a bit of NPC dialogue about it, but Lagiacrus is still the one that shows up in early quests, and has the whole "You need to kill it because it causes earthquakes!" storyline like in Tri. Deviljho is essentially the High-Rank equivalent of the "invade an early quest" monster, as it appears (and even gets a unique intro) in a Jaggia slaying quest. Flagship monsters don't always have a major role in the "storyline" of the game. As one of the anons said above, Nargacuga didn't have a particularly prominent role in Unite.