The Forbidden Demigod

It was not my fault that my friend turned out to be a forbidden demigod.
Allow me to explain.

My eyes popped open. They then fixed onto one of my friends, Elizabeth. She had woken me up from my sleep, and I was waiting for her explanation. I gave her a dirty look, and she started to explain.
"I need you for a quest."
Mumbling, still groggy from my sleep I said snarkily, "As if."
Elizabeth looked at me with a pleading look. Rolling out from my bed, I looked to her, waiting for an explanation. Why would she want me, of all people? A mortal. Someone whose powers were nothing compared to hers. A demigod. In fact, that's who I was constantly surrounded by. My fault, though.
"You're the only one who can use mortal weapons," she said, as if that was an explanation that solved everything. Rolling my eyes, and pushing off the fabric blanket, I asked her why that, of all things, is important.
"Just in case."
"What? You are incredibly powerful, and you have swords and arrows that could kill anything,"
"Except for mortals."
"Why would you need to kill a mortal? Isn't this quest to the Underworld?"
Truth be told, I'm an eavesdropper. I constantly listen to other people's business, and I heard Elizabeth talking about this quest proposition with her friends, Jane and Beckie. Jane had shoulder-length, dark brown hair, and was the daughter of Hebe. Because her mother was the goddess of youth, there were constant rumors that she would stay young forever. Beckie was the daughter of Persephone. She had slightly long dirty-blond hair and warm brown eyes. Always perky, She was like the spring. Elizabeth, who had elegant, platinum blonde hair, but she preferred a curly red hair wig. Ever since fifth grade, which was when I first met her. Here's the thing about Elizabeth, though. She had no idea who her godly parent was. She never brought it up, but I knew better. Being a leader here at Olympian Middle School, I knew that most students know their parents.
But not Elizabeth.
Sorry for my paragraph of exposition, but, here at OMS, things were a little different here. After 5th grade, those who are detected to be demigods are blood-tested to find out who their godly parent was, or if they were even a demigod. Then, they are trained, and manifest their powers. Elizabeth was tested, but no one could read who her godly parent was.
As for me, I chose to stay here to train the demigods. To be a leader. It was more action than anything I would ever get in my mundane life, and even if it was hard to say goodbye to my family, I visit them on breaks and stuff. I enjoy training the new demigods, and I've learned a lot of important skills.
It's still hard though, to not feel less.
Anyway, I propped myself up on my bed, and Elizabeth asked,
"How do you know it's to the Underworld?"
I gave her a guilty look and said, "I'm a damn good eavesdropper."
Elizabeth shifted, and whispered, "Did you hear about the incident?"
"No, I was touring that new student, George, the son of Hephaestus."
Elizabeth was about to drop the subject when I asked, "What the heck happened?"
"A mortal tried to break in."
"Bloody hell," I said in shock.
"They're gone now, thankfully,"
"Are you scared for your safety?" I asked, full of concern now. The only mortals permitted on these premises are ones that chose this as their way of life.
"You know what happens when demigods try to use mortal weapons. We can only kill demigods and monsters."
Only. I played that word back in my head. I would die instantly if I tried to pull that. Only. I was finally fully awake, and I now realized the stakes here. My friend could die trying to find the truth, venturing out into the mortal world. If this mortal was crafty enough to break onto these premises, they surely could find a way to the Underworld.
I pulled out my gun from underneath my bed. I had dozens more, but no one needed to know that. You see, a divine law was put in place that demigods can't use mortal weapons. (Basically any weapon made after Ancient Greece/Rome), The penalty is simple, like a gun exploding in your face. (Only a child of the 'Big Three' can have this rule not work on them, but that's a whole hassle.)
They say the reason for this law was to prevent a war with the mortals. I never understood this rule, until now. Divine beings sure-as-heck underestimate mortals. If a mortal was going to track down my friend, they were going to pay.
In the back of my mind, I felt like I maybe had a chance to prove that I am worthy. That I can contribute something, even compared to demigods.
Elizabeth looked at me.
¨Athena came to me and told me I have to go on this quest. But I have no clue how to get to the Underworld.¨
I smirked at her.
¨I may know someone who can help.¨