Just let that one roll around in your head for a while. Inter. Pleader. It sounds like it could be the name of a death metal, or mid-90's "industrial" band ("Tonight 9:00PM: Skinny Puppy, Interpleader, Revolting Cocks. All Ages!"). Or maybe it's a melancholic person who spends his days gnawing away at his own psyche. Or, it could be the name of a mind-eating brain-demon in a sci-fi story ("The Interpleader within him had reduced Commander Riker to a frail husk of a man, weakly crying for death in the corner of his containment pod."). It sounds so malicious, so demonic.
But, it's really just a legal term for a form of legal action where one party can force two other parties to settle a dispute - ex. a life insurance company can force two potential beneficiaries who each claim the same insurance benefit to settle the dispute in court before paying anyone. I suppose someone probably thinks such an action is malicious, but sadly, it's not really demonic.