Liam and Trouble.
Liam was, in fact, in his bedroom deep into his music. It was the time of evening where he wasn't doing anything with friends, dinner was coming up, and everyone was kind of just doing their own thing before said dinner. Usually studying as it were, and in Liam's case that meant getting alone time with his music while everyone else did their own thing.
For once, no one was in the room with him, yet Liam still had his headphones in, which were connected to his headphone amp, which in turn was connected to the guitar in hand. This meant all sounds coming from the guitar were going through the amp, and through his headphones, so no one else could hear what he was playing; and yes, while he was protective of his music, this also meant he wasn't being absurdly disruptive.
Sitting back in his bed, guitar held over his chest and stomach as he threw his fingers along the neck and frets, he had his eyes closed and sketched out a rhythm for the song 'Everytime We Touch' by Cascada. Once in awhile he'd open his eyes and jot something down on his scroll next to him, but otherwise he was completely oblivious to the world around him; that included the green shield around the school and the call for a lockdown. Instead, at the moment the lovely Trouble made her way inside, his eyes were shut, dressed in plain white t-shirt and a pair of sweatpants, with one leg up tapping out to the rhythm he was playing in his own ears, head bobbing along in beat.
He seemed, and it wasn't all that surprising, to be completely unawares of her arrival.