Mirin and Orn had moved in with Colin - forever Mr. Stone to Mirin. It was a little strange being back at the cavern, now her home, and dealing with two infants that were utterly dependent on her. She fit in with the routine better than many her age simply because she could communicate with her children already. She went into Reggie's mind to soothe him with vivid images of bears, and went into Regina's mind in turn with images of butterflies. They, in turn, sent images back to their mother - their needs and desires. It wore her out to be in constant contact, but no one could ever say she wasn't a vigilant, attentive mom.
Then there was the issue of Colin, Mr. Stone. He adored the babies, even if he was concerned about their size. He busied himself with their care when Mirin needed a rest, and even when she didn't, when he came around the babies sent out images of a large smiling face and the sensation of complete immersion and protection. But when the infants were sleeping and the cavern was quiet, Mirin could sense the restlessness in Mr. Stone's heart. She'd grown up seeing Mr. Stone and Mrs. Stone together, Colin and Sanria. The guilt she felt was the fact that it was her father that was driving a wedge.
Now, after a bit of time, Mr. Stone seemed even more agitated and tense. He paced more without realizing it. His jaw was more set, and the eyes that watched the babies were more distant. Mirin chose at that point to talk to her father.