"It's nearly 4:30 in the morning! Where the hell is she?" Alec Lightwood paced back and forth, observed by his boyfriend, Jace, and Clary.

Magnus attempted to calm his panicky boyfriend. "Darling, she's technically an adult now. If she wants to stay out late, you can't stop her."

"Like hell I can't! She's my baby sister," he practically hissed through clenched teeth.

Jace stretched lazily and put one arm around Clary before offering his Parabatai a small smile. "Alec. Chill. You know how Izzy is. She probably crashed at a friend's place." But anyone who knew Jace could see the brotherly instinct rearing its head.

Alec turned to face them all. "We all know that's not what what she's doing. She's out partying and drinking and," he took a deep breath, "probably hooking up with someone. Again. We can't let her keep doing this. I'm her big brother, for angel's sake. I'm supposed to protect her. Keep her out of trouble."

For the first time, Clary spoke up, "Alec. This is normal. I mean we're young. Izzy is 20. It's only natural that she goes out and..." Clary blushed, "explores and has fun."

Jace grimaced, rethinking his previous statement, "Ya know, I think I actually agree with Alec on this. She's never home. When she is, she's tired. She doesn't want to tell us where she's going. Maybe her partying habits have gone to far. We should talk to her."

Clary and Magnus exchanged looks. They both knew that if Alec and Jace let their brotherly instincts over take them, the results would not be pretty. No matter how good the intentions, Izzy would flip. No... Izzy would...well "flip" was the understatement of the year.

Just then, Isabelle Lightwood walked into the library.