Ren had been watching, from one of the many secret rooms throughout the home, as Rey trained. Pleased with the way she gave so much into her desire to fight, and battle, and attack. He enjoyed watching her fall, her change, and in the darkness where he stood, invisible to her, he found himself intrigued. What's more, he found he'd been watching more of her since he'd felt that odd familiarity in her. There was something more there.
Tilting his head to the side, he was surprised when Lea entered and ran into Rey, nearly being wounded in the process. This. Yes, this would be a curious thing to watch; he could feel power emanating from Lea now, a different one, there was a coldness there. What did it mean? He was unsure, but something was different in her too, and he was curious how this might play out. There was no Ren, as far as they both knew, and Rey struggled to find control; she craved it now, how would this situation unfold? Ren decided not to join in with them, not yet, not until he saw more of this test unfold.