When Serenity froze in place, Rei knew it worked. Usagi could hear her. Now she knew she wasn't just grasping at straws. They could get through to Usagi, help her come back. And more than that, she now knew Usagi could hear them if they spoke to her. Perhaps she might only hear if she was close to the surface as she was now, but it was worth it to continue addressing her as long as Rei could sense her. Of course, she also knew continuously calling the Princess by Usagi's name would only anger Serenity, but the fire senshi would pick and choose those battles depending on how things developed.
While she originally intended to stand infront of Serenity and look her in the eye while talking to Usagi, the light of the Ginzuishou made her slow down. And then the ghost image of Usagi made her stop dead in her tracks, her eyes going wide. "Usagi..." she breathed, then heard the apology. "I know it's hard, Usagi, believe me. I know the pain of losing someone. But you have me, you have Minako, and we aren't abandoning you!" But the the ghost image was gone before she'd even finished saying that. But she hoped that Usagi heard her. She wasn't going to let Usagi stay in there forever. If it was the last thing she ever did, she would get the bubbly teen to come back because she missed her. Rei wouldn't readily admit it, but she missed Usagi. The priestess needed her just as much as she needed Minako and the rest of the senshi.
Then Serenity was back to herself and Rei narrowed her eyes a bit. She cast a glance at Minako, wondering if Minako picked up on just how Serenity had chosen those words. Turning back to Serenity and walking after her, Rei wasn't going to relent. Not now. This could very well end disastrously, but at least Minako was there for this. "Are you so sure about that? Usagi is far stronger than you may think." Rei did think Serenity under-estimated Usagi, if only because she currently had no feelings of kinship towards the Princess while she did care about Usagi. She cast another glance at Minako, wondering how to press the Beryl awakening her issue. Minako usually was a little more tactful in her word choice.