Prickle finished her homework as her abductor paced restlessly. Once she was done, she tucked everything away in her saddlebags, making sure her costume remained out of sight. "I'm going to go to sleep."
"Huh? Oh! You're really well-mannered." Immovable smiled. "For being foalnapped and everything, I expected more complaining."
"You're not going to hurt me, right?" Prickle laid down on the stone floor and set her head on her bag as a sort of pillow.
"Right," agreed Immovable. "I'm here to challenge Tiny Titan, not a random foal. Geeze, what kind of pony would that make me?"
Prickle went to sleep, or so she made the appearance of. She closed her eyes, but her ears strained to hear every movement, waiting for things to calm.
"You have to come," came Immovable's voice, almost sad in tone. Prickle could hear her settle down. "Have to..."
Things were quiet save for a distant occasional drip that sounded somewhere in the caves. Prickle cracked open an eye and looked around cautiously. Immovable was across the room, her chest slowly swelling and contracting in gentle rhythms of sleep.
Prickle figured she could just grab her things and flee, but that wouldn't solve the problem. She nosed open her backpack and got to wriggling into her costume as quietly as she could.
"Mmm?"
Prickle peeked towards her 'opponent' as she rolled over and let out a snort. Confident that sleep was still happening, Prickle finished donning her outfit and becoming Tiny Titan. She grabbed her bag in her teeth and trotted off, tucking it behind a rock out of sight before returning. She cleared her throat softly before announcing as formally as she could, "Immovable! I've come for you!"
Immovable jerked awake and scrambled to her hooves, wings spread in alarm. "What? Who?!" Her eyes came into focus on Prickle. "T-t-Tiny Titan?! You've come!?" Her wings started to fold back. "Of course you came. My cunning..." Her eyes darted around. "Where's..."
"She's safe." Prickle took a step forward. "This is between us."
"It is," agreed Immovable. "Our rivalry is meant to be!"
"Do you know what a rival is?"
Immovable blinked softly. "Eternal enemies, matched and enduring?"
Prickle shook her head. "I had time to think about it. That's not what rival means."
"Are you saying we aren't rivals?!" She looked furious, but also so very scared.
Prickle rose up onto two legs. "You are my rival! You just don't understand what that is."
Immovable tilted her head to the left slowly. "Well then, misses smarty pants, what is it? Are you trying to confuse me? It won't make me move!"
Prickle smiled softly. "I'll move you."
"You won't!"
Prickle raised a hoof to her smaller chest. "I will move you on the inside, which is more important. A rival is someone you compete with. It doesn't have to be someone you don't like."
Immovable's eyes gave the slowest blink. "Alright? But you don't like me."
"Do you not like me?" Prickle fell to all fours.
"I... you're my nemesis! My foil! You are everything I am not, and I am everything you can't oppose." She planted her bottom down squarely. "Your strength is meaningless!"
Prickle took a few steps towards her 'nemesis'. "May I try?"
"Of course," cried Immovable with a grin. "Try all you want. Try and fail!" She laughed the wild laugh of a pony that needed help.
Prickle stepped in closer and reached out with her forehooves. "I'm going to move you."
"Never!" Her face was a fierce mask of determination.
Prickle, on the other hoof, had a smile, a gentle one. She hopped up a little and grabbed Immovable around the neck. She hugged her.
"This is... a very interesting attack, but you can't pull me to the ground either, and you're barely trying. You'll have to do better than this, Tiny Titan."
Prickle pulled in closer and squeezed slowly harder and harder, being ever so careful. "You're not a bad pony."
"W-what?"
"You aren't." Prickle squeezed before dropping free. "We don't have to be enemies."
"Of course we do," cried Immovable in a hysterical shriek. "Even you're ready to throw me away!"
Prickle flinched. She hadn't expected that response. "I'm not throwing you away. I said we were rivals."
Immovable's ears twitched in a spastic movement. "If we're not enemies, but rivals, what are we?"
Prickle reached up a hoof and set it on Immovable's left foreleg. "Friendly competition. I'd... actually like someone I can practice on without worrying about hurting them." A thought came to her. "I'm sorry to bring this up, but did the ponies that picked on you try to punch you?"
Immovable's snout wrinkled. "They tried! I couldn't even feel their puny strikes. Why, are you waiting for your chance to hit me?"
By Celestia, that sounded so very wrong to Prickle. "Not... like that. Not to hurt you." She shook her head. "Immovable, I..." She faltered. She couldn't think of the right words. She cast her thoughts to comics. She was a superhero. What was the proper response? "Immovable... You are hereby my responsibility."
Immovable blinked softly. Her rock-solid stance broke. "What?"
"We won't fight against each other. We will fight... together!"
Immovable almost fell as if her bones were turned to butter. "I... what? I... I'm not a hero..."
"You could be," said Prickle with a little smile. "Do you want to be?"
"You'll... I'm... I'm your sidekick?" She let out a sudden laugh, hysterical, but hopeful. "Are you serious?!"
"If you want to be." Prickle set a hoof on her own chest. "We will be rivals, the good kind."
Immovable bounced to her hooves. "Is this a trick? You're trying to be sneaky!"
Prickle shook her head. "I'm not, but... even if I was, you wouldn't be moved by it."
"You got that right!" Immovable flashed a manic grin, but it faded almost as quickly into worry, eyes darting around. "Are you... really serious?"
Prickle turned slowly. She still had no idea which way led out. "I'll show you how to be a hero. Ponies will cheer when they see you, and even if they don't, it feels nice to do the right thing."
"But... we're... opposites."
Prickle poked her stalwart rival. "You have everything I want, as a super hero. You can't be hurt or moved if you don't want to be, and I'm as easy to hurt as anypony, I think. We're not... enemies, we're partners waiting to happen."
Immovable suddenly began to blush right through her costume. "I... never thought..." She suddenly dived for Prickle and plucked her up into a fierce hug. "I accept! I will be your sidekick forever and ever!"
It was just at that moment that Prickle realized she may have just agreed to more than she should have. As the damaged pony hugged her and professed her delight, Prickle wondered how she would handle it.
"There's somepony I need to introduce you to, but let me talk to them first."
Immovable set Prickle down carefully. "Nopony can move me, except you. I'll meet this pony when you tell me to. Until then, I'll be here."
Prickle glance around the dreary cave. This was a case that would not be solved with a swift kick, but it was not an enemy she would back away from. "You deserve better."
Immovable's confidence wavered. "Better?" She waved it off suddenly. "It's not the best, but I have... better... this was..."
Prickle pushed Immovable. She wasn't expecting it and wobbled from the force. "You're my sidekick, and I'm your mentor, so It's my responsibility to see you're alright."
Immovable's eyes moistened. "You're really serious, aren't you?"
Prickle sat up proudly. "One hundred percent! Don't try to stop me." She stuck out her tongue. "Even if you have fun doing that. I'm going to make things better."
Immovable leaned in on her smaller, younger, mentor. "I'm going to get in your way, it's my nature."
"You'll get in the way of bad ponies and protect good ponies from being hurt." Prickle nodded firmly. "I should go, for now... Uh... I've gotten turned around, which way is out again?"
Immovable moved to one of the tunnels, the plopped herself down solidly. "You'll have to get past me."
Prickle trotted around Immovable. "I have to go, but we'll play, soon, promise! There's so much to prepare. I've never had a sidekick before."
Immovable watched Pr-Tiny Titan trot away, her own chest tight with worry. "Did I just mess up?" She had her ultimate rival right where she wanted her, and let her go on the flimsy hope for more, later. What if Tiny Titan had said all that just to make her drop her guard?
She rose to her hooves with a heavy sigh. She would have to wait and find out. She didn't feel like sleeping anymore, so she paced and wandered the caves, trying to sort the chaos that raged in her mind and heart, which is when she tripped over an abandoned saddlebag. It belonged to that filly she had foalnapped. Oh no! "She'll get in trouble, and they'll think I'm a two-bit thief!"
Immovable grabbed the bag in her teeth. "I'll bring it to her before she even realizes. Silly Tiny Titan, you snatched up the filly and forgot to ask her if she had anything with her. That's sloppy work, rival."
At home, Prickle hugged her worried mother. "I'm sorry I was late. I was foalnapped."
Junebug blinked with wide eyes. "You were what?!"
"It's alright, really. I handled it." She put a hoof on her chest. "I am Tiny Titan after all."
"Well, Tiny Titan, go eat some food and prepare for bed. Did you do your homework while you were out?"
Prickle paled. She forgot her bag! It was back with Immovable. She was in so much trouble!
A brisk knock came from the door.
Junebug turned to face it. "Who's there?" she sang out in question as she approached.
The door swung open to reveal Immovable, in her costume still. "The filly forgot her bags. I wanted to get it back to her."
"Oh?" Junebug accepted the bags on the end of a hoof. "Thank you, miss?"
"Immovable. Have a nice night."
"You too."
Immovable trotted off, ignorant to how close she had come to her rival once more.
Junebug turned to her daughter, bags dangling from her hoof. "Was that the pony that foalnapped you?"