Isabel

“Instead of replying, Alec reached down and took Magnus's hands. Magnus let Alec pull him to his feet, a questioning look in his eyes. Before he could say anything, Alec drew him closer and kissed him. Magnus made a soft, pleased sound, and gripped the back of Alec's shirt, rucking it up, his fingers cool on Alec's spine. Alec leaned into him, pinning Magnus between the table and his own body. Not that Magnus seemed to mind.
'Come on,' Alec said against Magnus's ear. 'It's late. Let's go to bed.”
― Cassandra Clare

“So I’m your first ever Shadowhunter, huh?" Alec said when they separated at last.
"You’re my first so many things, Alec Lightwood,”
― Cassandra Clare, City of Heavenly Fire

“Jem is nothing but goodness. That he struck you last night only shows how capable you are of driving even saints to madness.”
― Cassandra Clare, Clockwork Prince

“Maybe warlocks only liked other warlocks. Though Magnus did seem to like Alec quite a lot.”
― Cassandra Clare, Welcome to Shadowhunter Academy