how to write like cassandra clare 101

Jace looked handsome as ever; his slender muscular body stood tall and rigid, impossibly strong and ablaze with power even after hours of fighting. The gold in his eyes was fogged over with a layer of concern, the sharp intelligence behind them ever so slightly touched by emotion. He looked like a statue carved by the gods, all gold and power and perfection. The tall gay was next to him. 

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“Jace was gold, catching the light and the attention, Alec was silver: so used to everyone else looking at Jace that that was where he looked too, so used to living in Jace’s shadow that he didn’t expect to be seen. Maybe it was enough to be the first person to tell Alec that he was worth being seen ahead of anyone in a room, and of being looked at longest.
And silver, though few people knew it, was a rarer metal than gold.”

Herondales have sex in caves, Blackthorns have sex in every book.