Mettle – Courage, fortitude
Alphard and Sirius
)O(
Alphard had never been a brave person. He did not mind that – bravery, to him, was very little more than an excuse to act foolishly. Oh, he had his moments of bravery – standing up to his sister and brother about the treatment of their children, for example – but he was not brave.
Sirius was so different. He lived and breathed risk, and Alphard thought he had never seen such a happy child. He – Alphard – admired Sirius's courage.
So, when Sirius's courage got him disowned, Alphard vowed to help him.
Even though it meant getting disowned himself.