He was worried about his team.
Robin reminded himself as he walked through the darkened cavern, trying to classify the anxiety welling up inside him. Terra's betrayal had shaken them all, but two in particular seemed to have been most affected. One of them, Beast Boy, was obvious in his pain, and was quite understandable in it. He'd been the closest one to Terra after all. It was the second that surprised the Boy Wonder.
Raven had barely spoken to them since her encounter with the earth mover, and Robin had the distinct impression she was pulling back into herself. When they had regrouped in the underground cave after their defeats, the leader had drilled all of them individually on their battles, hoping to find something to use to plan out an effective counter-attack against Slade's new apprentice. They'd all told him what they knew readily enough, except their dark friend. Robin had been forced to push his authority as team leader to finally get her story. She seemed to have lasted the longest against their opponent, and had been finally taken down by psychological combat instead of physical, becoming enraged after Terra taunted her about actually trusting her.
'That's what did it.' He thought to himself, trying to piece together the puzzle that was Raven. 'She's a prisoner within her own mind, locking herself away from us to keep us safe from her powers. Her distance and walls are to keep others from breaking her cell, and only a trusted few are allowed to see her caged self. Terra gained that trust and betrayed it, using the weaknesses she'd seen within Raven to take her down on the inside. No wonder she's withdrawing! She hates being weak or manipulated and both had happened in that breach of trust. She thinks the only way to keep that from happening again is cutting us all off - she's just going to hurt herself more if she isolates herself-' He sighed, pausing and changing the direction of his wanderings, following the meditative chant echoing through the stone corridors. 'Time for another pep-talk.'