[He senses that quiet undercurrent of 'you two are dead if you fuck with us'. But fine, then. This isn't a battlefield and he doesn't care to ruin things right now. Besides... isn't it more fun if the other person agrees to the highest of stakes?]

Tch... Fine then! While I can fuse part of my soul at any time... To transfer others, there's a caveat.

That Soul-Body Transfer is a 'penalty game' ability. To use it, the target needs to have either lost a game or been rendered unable to play after agreeing to join it. Technically, any competitive activity counts as a game as long as it's acknowledged as one... But it still requires that victory.