So the Golbez dialogue in the trailer is a flashback addressing the Four Fiends even if the trailer tries to misdirect to make it seem like he’s imploring the WoL. But my theory is the flashback where Zero lore dumps on the two knights of Baron and we see the giant Highlander with eyebrows, pale hair in a new style, and the likely original identity of Golbez. The second knight, the dark haired Midlander, looks like Zero - so my theory is that he’s her father of whom we’d learned nothing about. This Echo flashback isn’t from Zero’s pov but her mother, and Zero is retelling the story she learned of how her parents met.