This faction was initially named House Stormsong during early alpha.
The Storm's Wake acts very uncharacteristically during the Horde's Stormsong Valley foothold quests. They are able to gather a large army against the Horde, uses dark magic to summon sea beasts against them, show cruelty against animals and are led by an officer hiding her face behind a malevolent-looking mask while saying things like "He who lurks below shall wear your skin as his cloak". This points to them working for House Stormsong, maybe showing that these events are happening before the split between Wake and Stormsong. Even the Horde soldiers noted how abnormal they acted.