The other side of the river is out of view, but Sigma waits. If Devero does not return, then he may well need to send someone to retrieve Devero - it will not do to lose an ally to the abyss.

But Devero does return, for a moment, before he disappears and in his place is left...a dog.

A dog, he remembers, that Siebren had seen around campus, back when he had thought himself to be Professor de Kuiper.

Ah.

He hesitates a moment, then nods. "Gather yourself," he tells the dog. "I will return with another soon enough." He gives that a moment to sink in, then floats off back to the front line. True to his word, he will return soon enough, but for now, Devero has a little time to get his feet back under him.

(The difference between Siebren and Sigma is obvious here: Sigma does not stop to pet the dog.)