Mendacium (джен)

"Why are you doing this?" Shouta couldn't help but ask. Really, this kid couldn't be much older than his class, and he was already out his risking his life to fight... and was good at it. That was the worst part of all, that a child would act like an experienced soldier in the face of danger. "If you stop now, I won't report you. You can just go on home to your family, and maybe try to be a hero-"
A laugh cut him off, but it was more sad than condescending. "Mr. Trash Bag, I'm doing all I can to get home. But like hell I'll be a hero. I've been used by the government too much." A slight European accent colored his words, and his Japanese was a little hesitant, but the determination was clear. "I have to admit, though, your quirk is really awesome. The ability to stop others' energies... remarkable."
The boy tensed, and Shouta activated his quirk on reflex.
"Too bad it doesn't work on me, then. Can't erase what you don't have, after all!"
OR: Edward didn't want to help Truth. He didn't want to go to a different world to defeat yet another Father. He didn't want to be on the run again.
He also wanted his brother back. The choice was obvious, even if Truth is a massive asshole.