Board Thread:Destiny Forum/@comment-5650583-20131111135917/@comment-5650583-20131208175444

Sangheili swordsman wrote: The Fallen likely speak English due to the reason that the Covenant Empire learned to. It is strategically advantageous to understand the language of your enemies. Applications of this skill are intercepting and translating enemy transmissions, understanding battlefield directives shouted by the enemy, interrogation, and simple communication.

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Though going back to the Fallen, Rixis' application of his English was obviously to convey his malicious intent to the Guardian intruders, more than likely to intimidate them. Yeah, the ability to trash-talk your enemy in their own language should never be underestimated.