(Y/N) and the Amulet: Friends or Foes

Part 1

   Some time had passed. Since the first time you opened that packing box, and found the mystical amulet in your bedroom. Since you were transported to Equestria, as an experiment for Twilight Sparkle, who wanted to see if you could find the magic of friendship for yourself. You were 14 now. A freshman in high school. Of course, your visits to the pony world had become less and less, but you still visited whenever you could.

"So, make yourself at home," You say as you enter your home. You've made three friends since your fateful visit with the Equestrian race of Ponyville, all those moons back. High school was looking very promising, as long as you could keep the secret that you visited magical horses in your free time.
You invite the three in, in this order: First is Chanel, a blonde girl with some of the biggest curls you've ever seen, and even bigger glasses. Second is Tristen, an older boy who likes your taste in music a whole lot. And finally, your newest friend, Rudy, a red haired kid your age, with freckles and very bright green eyes. They preferred not to be gendered.
"Thanks for inviting us," Chanel says happily.
"Yeah, so where's your records?" Tristen asks.
You giggle, "We'll have time for all of that, I promise," you assure them, then glance Rudy's way. They're looking around at your photos hanging on the wall. You shut the door and lead them to your bedroom.

After you've had your fun, with movies and the meal your mom prepared, and talking late with each other, you find yourself growing tired. You're sitting on your bed with your pillow against your chest as you listen to your friends talk.
Tristen is going on about how to play the guitar. "I learned when I was pretty young. It was easy, my grandpa taught me where to put my fingers and the chords just came naturally."
"Good for you," Chanel says, her voice lacking interest. "I can't carry a tune in a bucket," she laughed. She seemed sleepy, too.
You chuckle at that, glancing towards Rudy. "Hey," you say.
Rudy looks up, "Yeah?"
"Are you alright?" You ask.
Rudy shrugs, "This is my first time at a sleepover." They admit.
You smile, moving onto the floor to sit beside them. "Mine too." You admit, shrugging as well.
The two of you share a soft, somewhat awkward chuckle.
"Is there anything I can do to make you more comfortable?" You ask.
Rudy looks off with a soft hum, thinking to themselves. "Uhh... I could use the restroom." They say suddenly.
"O-oh." Well that caught you off guard. "Yeah, the bathroom's right there," you say, pointing over your shoulder.
They stand up and walk off in the direction you point them toward, leaving you and the other two alone.

A while had passed. Chanel was asleep on her sleeping mat. Tristen had offered you guitar lessons, which after a while of nervousness, you accepted. You thought your pony friends would be very proud of you for trying something new with a brand new friend. And then you began thinking about your friends. Twilight Sparkle, Fluttershy, Pinkie Pie, Rarity, Rainbow Dash, Applejack... You missed them, really.
Who else were you missing?
Rudy.
They had been gone for almost a half hour.
Tristen was falling asleep, so you scrambled up quickly and went to the bathroom. The light was on, you could see the glowing from underneath the door. You gently knock, "Rudy? Rudy, buddy?" You ask, worriedly.
No answer.
You jiggle the doorknob.
No way in.
You run back to your bedroom, going to your dresser. You open the drawer where you left your box, and more importantly, your amulet. The box was already ajar, and after some quick shuffling through the packing peanuts, you realize your amulet has been stollen. From the top drawer, you pull a bobby pin out, and go back to the bathroom.
Thankfully you knew how to do this.
Jamming the bobby pin into the doorknob, you felt around for the lock and flicked it left. You opened the door, to find an empty bathroom. Rudy was gone.
"Oh no..." you breathe, stepping in.
That was your only way into the pony dimension, and Rudy had it around their neck. What were you going to do now?