A Surprise Revelation!

You wanted to have some time to yourself, instead of feeling like a pseudo-Robin for the Detective, so instead of resting, you turn back around and head into the training room. You look around for something to work on your boxing form, your physical strength.

There was a cylindrical punching bag about half as tall as you. You bear your bare knuckles in front of it, keeping your feet apart as you punch and jab at it quickly and strongly.

You remembered from YouTube videos in the first days of your heroics. They mentioned how to keep your weight balanced in both of your feet; remembering to breathe deeply during your workout; and aim for spots around the bag, as well as on it. You kept bopping and whacking, and whacking and bopping it as you watch it swing on its chain.

During it all, you felt your heart hammering against your chest from your workout. Strangely, you could feel a spark in the back of your mind from when you began, and the brief feeling seemed to steadily become like a sparkler; this 'instinct' to hit harder seemed to itch inside your skull until you throw your arm back. If you had paid attention to anything but the punching bag, you would've seen a brief ghostly image of... a mantis shrimp?

You came out of some kind of daydream, and remembered one moment that you wanted to make a tremendous hit; and now? You notice that... the punching bag was missing? Just a broken chain link at the end! You look around, and walk around the gym to find it on the other side... near the exit's wall.

'What just happened...?' you ponder. You try to think back to what happened before you... blacked out, you suppose?

You pull your arm back, kept your eye on your target, and... You thrust your tight fist against the bag with such blinding speed and strength! Not only did you snap the chain, but the bag left a big imprint in the wall, had ricocheted off and left a tiny imprint on a perpendicular wall, bouncing off of that instantly to the other side of the gym! With the top pointing towards the exit.

That backstory? Reliving it in your mind? It was terrifying... You never had such strength before; you stare absentmindedly at your pink, sore knuckles. The pain was the last thing on your mind, as you quickly left to find a doctor.

Luckily for you, one you knew was nearby.