User blog comment:Master Sima Yi/Assassinews 25-03-'13 — Assassin's Creed IV: Black Flag gameplay trailer/@comment-4999424-20130423151352

ACIVBF Main Charecter details & Templar plot revealed.

From Article:

Kenway is extremely adept at stealth, and will have the ability to hide behind doorways to avoid patrolling guards. He will also be able to blend seamlessly into groups of prostitutes (as opposed to courtesans in previous games) to elude his enemies.

The Templars' role in the story pertains to their interest in a specific location in the Caribbean—a location also critical to the Assassins. In case you haven't yet guessed, the area in question is the Bermuda Triangle, which players will explore as a part of the mystery of the advanced race of precursors.

ACIVBF rival Pirates system revealed.

From Article:

Game Designer Ashraf Ismail revealed, in interview with PC Gamer on April 20, that Kenway won’t be sailing the waters alone as the game’s protagonist will have to constantly fight off attacks from rival pirates.

Players will be able to sail to any part of the game’s map at any point, put obstacles such as these increasingly powerful rival pirate crews, will provide a constant threat in the Caribbean waters. These enemy pirates want what any sea-fairing scallywag wants; to relieve players of their cargo, ship, and life. While gamers can sail anywhere, these rival pirates provide a system that requires players to upgrade their own ship before venturing into such dangerous waters.