Faith Spring
If Ryu thought that Sarriel was fearing for her life, he was correct, but not in the way that he might expect. The only thing that could make Sarriel feel fear was failure, and the only way she could fail in her eyes is if she never met her goal to resurrect her Clan and seek revenge on those that had eradicated them to their final member.
Whenever she felt fear, it was because of the weight on her shoulders. If she had nothing to care for but her own life and death, there would be nothing that could make her even flinch in the face of a tall mountain.
In this respect, Sarriel's trauma was even deeper than Ryu's own. Ryu's mother was still sealed in a mountain of ice, his father's whereabouts were still yet unknown, and his great grandfather was very much still alive and doing just fine.
Ryu didn't understand what it meant to be the last. He didn't know what it meant to be the final hope. He didn't understand the weight that came with it.