As tightly as Sans-Serif may be holding him, S-4 still isn't functioning properly. Panic over abandoning Sans has been replaced with panic that Sans-Serif may be next, and he's still choking on his own sobs when Tauriel finds them.

Her embrace is overwhelming, but more so is what Sans-Serif calls her. Mother. He considers her a mother. She does care for them and love them as dearly as the bird in that book, but he doesn't know if that is right. He's just more confused, and more emotional at the thought. Slowly, he turns his tear-filled eyesockets to her.

"Mom...?"

If she's really their mother, she'll know what to do.