We are the last ones

Part 2

And there they where.
Her house.
Jace grinned idiotically as he drew a stamina rune on his arm, though Sebastian didn't understand why he did. It's not like they were going to fight.
Then his stomach twisted as he understood. Clary.
He whipped his own stele out, his face contorting into a snarl as he drew a demonic rune of victory and chaos on the floor board.
Jace rubbed his hands together and smirked, probably thinking at what improbable sex position he could attempt on Clary. Maybe he was even thinking at inventing a new sex position with Clary. They'll probably call it the Red Hot Demon or The Red Hot Shadowhunter. Or Grab My Seraph Blade.
Enough. He said it out loud.
Jace didn't even notice, preoccupied as he was with his Clary frenzy.
"Go and get her," Sebastian said, trying to sound calm.
Jace's eyes sparkled as he took the stairs and left him alone.
Sebastian's fingers hooked around the doorknob of what he assumed was the kitchen, he twisted it and entered.
The kitchen looked like the one of a family, plates strewn on the counter and a big bottle of water for late night drinks.
Then, footsteps.
Sebastian halted as his ears picked up the sound.
Werewolf? No, too light. Jace? No. There would be double footsteps. So. That left: her.
He stopped dead.
Then hid behind the counter, like a child.
The door opened. He heard breathing, light steps. His lungs stopped working.
Then, slowly, he stood up.
There she was, red hair in a messy bun, short, like Clary. Her head was turned, her scarred shadowhunter hands rummaging in the cupboard for what was probably a cup.
Then, sound of shattering glass and a gasp.
"You," she hissed.
"Your son," he corrected.
"You," she said, voice rising and breaking off, hands shaking, "are not my son anymore than Valentine is the man I love."
That words lit the spark Sebastian had fed for all those years. He reached for his dagger then put it to his own mother's throat.