The sword bounced against Petra's hip as she entered the BART train. The passengers didn't give her much thought, too used to the sight of Knights these days to care. Petra was relieved; she didn't want anyone looking at her.
She thought about the manuscript in her backpack, the one with scarlet-inked words attempting to crawl off the page. It called to her, murmuring like wavelets teasing the very edge of her consciousness. Her backpack wiggled as the manuscript tried to escape. The Mage had warned her that it was dangerous, and had paid her extra to transport it, but Petra hadn't taken him seriously.
When was she going to learn?
She thought about Severin, her teacher. His way of warning her had been to ask her to pick up a flowerpot from the deserted corner of his garden and bring it to him. She had shrugged, pushed her blue curls out of her eyes, and picked up the pot with one hand. The pot had started vibrating and a slick muddy creature had popped out. Petra had yelped and dropped the pot, which had broken into sharp pieces, causing the little seed spirit to crawl away in a huff.
Petra recalled how Severin had looked at her, the only sign of his displeasure the high lilt of his dark eyebrows. "Never handle the items with anything less than complete caution, especially now that magic has awakened in the world. You must always be prepared. Mages are lost in their minds, the call of magic too strong. They will forget to warn you, and you are the one who will end up paying the price."
Petra wished Severin was riding the train with her. This was her first transport, and her nerves were on edge. The rails screeched and sang as they soared over Walnut Creek, but they couldn't drown out the hymn of the manuscript.
"Ways to capture and manipulate motion," the Mage had whispered with barely contained glee when she had asked what the manuscript was about. "Be careful with it!"
Of course, the way she was going to keep it safe was taking it on a crowded BART train. Smart, Petra.
It was the only course of action, seeing as how her scooter was still in the shop.
"19^th Street Station," the conductor's voice called out. 
Not many people came on, and the BART train left the brick walls of the underground station, smoothly rising above the freeway. Weak sunlight illuminated the greyscale colors inside the train car, glinting slightly off metal-studded boots or smooth luggage sets. Petra kept her eyes glued to the open door, watching who left and who came in. She'd seen a couple Knights-in-training and one Mage, but most were regular folk going about their day. The discovery of magic and the resurgence of Knights hadn't changed the Bay Area much, except that it was no longer unusual to see kids "sword"-fighting on the shores of Lake Merritt or taking alchemy classes from Mages at the Exploratorium.
"West Oakland Station."
Petra shifted and put her hand on her sword as soon as she saw him.
The cloak he wore was green velvet and covered his face, but she could see the glittering Words of Protection painted on the underside as he strode into the train car. Only fully trained Knights could wear clothes or armors with the Words and Petra instantly took notice. All the seats were taken, so he grabbed a pole, rings stacked on his fingers. His nails were the same color as his cape, which swayed as the train took off. What bothered Petra was that it was still swaying.
She reached down, pretending to check on her boots so she could scope out his cloak, but as soon as she moved down, she heard the tell-tale whistle of daggers hurtling through the air.
Grabbing her sword, she rolled onto the aisleway of the train car, the daggers just missing her. Those hadn't been rings on his fingers.
Someone screamed as the daggers landed in the seat where Petra had just been sitting.
She knew she had a couple seconds while the Knight reached for his sword, so she leapt up, sword at the ready; it was not as long as the ones most Knights used, but that meant she could be quicker with it.
The ringing kiss of their swords crossing filled the train car with a harsh sound that battled the screeching of the rails. Out of the corner of her eye, Petra could see passengers covering their ears. She didn't have much time to look as the Knight pushed forward.
Petra gritted her teeth and held her ground. Her backpack was clipped to her leather armor in various places and locked in on the back, so she wasn't concerned about losing the manuscript. She just didn't relish having to duel in a BART train.
"You couldn't have waited until I got off at Embarcadero? Lots more space to parry over there," she mused with a wild grin. The other Knight chuckled and charged at her, sword swinging from above his head.
Petra ducked into a (luckily) empty set of double seats and slashed at the Knight's cloak. The glittering Words of Protection went out like fairy lights blinking off. Then she kicked at him, her heavy boots connecting with his chest as he tried to lunge at her.
Petra took advantage of his momentary stumbling to push through the sliding doors connecting the train cars. The whoosh of air between the cars overwhelmed her senses for a moment, and she nearly lost her own balance. Then her hand found the other door and she pulled it open.
Petra ran through the train cars, sword kept close to her body so she wouldn't accidentally run anyone through. The train careened over the industrial parts of Oakland, dotted here and there with colorful Mage gardens and Knight encampments.
Suddenly, a rope wrapped itself around her arm, jerking her back and making her fall on the ground.
One hand held her sword tightly and she pulled herself upright a seat. There weren't as many passengers at this end of the train, and she moved into the more open area in front of the doors, ready to fight.
Swords danced together hungrily, meeting in a shiver of metal on metal. Her body twisted as she met the Knight's thrusts and parries; she felt like a cattail in the wind, lithe and powerful against the currents of motion. Petra remembered everything Severin had showed her, muscle memory springing into action and freeing her mind to gather information. The Knight's face was still not visible to her, but his style was somewhat familiar . . .
The train began its descent down into the tunnel under the Bay, and the other Knight stumbled back, unprepared for the change in motion. Taking advantage of his sudden weakness, Petra pressed forward, slicing through his cloak and pinning him to a seat with her sword.
Before she could rip off the hood of his cloak, she heard a bubbling sound.
The bubbling turned into full-throated laughter and the Knight pulled off his hood to reveal a familiar face.
"Severin!" Petra exclaimed with a pout. "You were tailing me this whole time?"
Her teacher looked up at her, his eyebrows raised joyously. "I wanted to be sure you could hold your own on a transport. Call it a final test. After all, far worse than me may come after what you carry one day."
Petra rolled her eyes. "Great. I thought you said I was finally ready to take on transports on my own."
"Oh, you are," Severin said with a grin. His black beard covered most of his face, making him look harsher than he really was, but Petra could tell he was delighted with himself. (Perhaps her, too.)
"Didn't I tell you though? You must always be prepared!"
He was still pinned to a seat and patted the one next to him. 
Petra sat down, looking forward to feeling of fresh air on her face when they reached the city.
"So, you going to unpin me or what?"
Petra grinned. "Not yet. I think it's my turn to teach you a lesson."