Erebus smirked, fully expecting that question. He waited for a moment, picking at the invisible and nonexistent dirt that was underneath his long, claw-like nails before bothering to respond.
"If you win, then I'll give you the contracts of every soul I have collected over my lifespan." He knew that this was a huge proposal, and it raised the stakes of even the original bet drastically, but Erebus wasn't fazed. Nothing was more thrilling than a good gamble, after all. He paused, needing a moment of dramatic suspense before continuing, his firey eyes not breaking eye contact with Icares.
"And if I win, I get to collect your soul. As dark as they may be, every demon has one. Even I, as surprising as that may be. You will cease to be your own being, and you will become nothing but a puppet controlled by my string."
He held out his hand, a glowing ring of dark magic forming around his wrist; a common occurrence to happen whenever two demons made a bet with each other. "So. Do we have a deal?"