Your OC can either be mistook for a villain, or a villain

Aquamarine: (imgflip.com/i/a2wz9r) Hi, who are you guys?

Death Gatling: *He fired a warning shot upwards* "Don't play dumb “Hero Hunter”!"

Stinger: "You seem wise. Surrender, and there'll be no fighting."

Aqua: I’m literally like… I think a teenager, I don’t remember.

Gun Gun: "Quit messing around!" *He drew both his guns and fired them simultaneously*

Aqua: woah there pal let’s take this back a notch. I’m not even in my dark world form

Death Gatling: "We'll calm down if you surrender, and if not... You can guess..."

Gun Gun: "You've got 5 seconds!"

Aqua: what happens if I surrender?

Death Gatling: "Life in maximum security prison."

Aqua: then no can do, I kinda have a life *grabs knife out of pocket, then stabs the ground to make a dark fountain*

Gun Gun: *He immediately shot with both guns aimed at Aqua's head*

Aqua: *seals fountain, they can see he dodged the bullet* can we calm down please? *is in 2nd form*

Death Gatling: *He suddenly switched to Death Shower, dramatically increases the gun's firing rate in hopes of catching Aqua off guard*

Aqua: what the? *uses the metal umbrella again*

Death Gatling: *He continued the fire, the umbrella denting significantly, the bullets about to pierce*

Chain'n'toad: *He launched his kusarigama at Aqua's feet, aiming to trip them*

Aqua: *jumps and uses the umbrella as a glider, to then kick the guys guns out of his hands* I won’t… fight…

(using a metal umbrella as a glider?)

Aqua: *fails miserably, it's a metal umbrella* well that didn't go how I planned... but my points still stands

*A dozen arrows suddenly rained from from above as Shooter re-equipped their arrows*

( btw I'm not that well versed in Deltarune's power system :P )

Aqua: *grabs pen and makes an iron umbrella* know this is closer to a fair fight *copies Jevil's face*

Shooter: "Be careful! This guy seems dangerous!" *Poison leaked from the arrows down the umbrella*

Chain'n'toad: "Clearly stupid if they try to beat all of us...." *They launched their kusarigama at Aqua's chest*

Aqua: *muttering* why couldn't they just have magic attacks?

Chain'n'toad: *The kusarigama slammed into Aqua*

Gun Gun: *He shot the ReviveMint out of Aqua's hand* "Don't let them get a moment's rest!"

Smile Man: *His kendama's giant ball was launched towards Aqua*

(images included for visual aid)

Aqua: *jumps up and eats the ReviveMint, making the weapon disappear from his chest* you know, you’re only helping me get stronger by attacking me *points to TP bar on pen* the more of this I have, the more stuff I can make *makes a shield, just before the ball hits him*

Gun Gun: "You haven't launched a single attack. You can't stay on the defense forever." *He reloaded*

Shooter: *He launched a single arrow at Aqua's chest*

Stinger: *He charged in* "Fight back!"

Smile Man + Chain'n'toad: *They retracted their weapons*

Aqua: … *weaves, dodges, and makes more defensive things as the attacks come, obviously refusing to fight*

Death Gatling: "Move!" *He yelled*

*The other heroes quickly got out of the way, and he began shooting out of his intimidating gun, the stray bullets tearing down trees*

Aqua: *starts running towards them, as they draw something, dodging to his best abilities*

Aqua: seriously? I just want to get to school! *makes a ReviveMint*

“I just got here. Why are you trying to capture me I haven’t done anything yet?

an ambush? how fun this will be! *he seems childish*

(what exactly is your OC? It reminds me of a Doors entity)

Death Gatling: "You're the monster who "hunted" all those heroes?" *He aimed his gun towards them*

Wild Horn: "Surrender before anything gets out of hand."