For a warlock, recognizing your patron is child's play. Most devils shapeshift, so it's not physical appearance that tells you, it's their aura. You can sense it since you're using the same magic, even if it was given to you under a contract, its still your patron's. So when you quickly try to do your duty as someone with magical power, and kill the monsters that have spawned due to the blood moon, you pause. It looks like your patron, a devil named Ischyros, but you can tell it wasnt him.

You try to ready up a spell but are hit with a surge of pain, everything is blurry, and you can't tell what's happening or how much time has passed, but once you're slightly more aware, you sense Ischyros' presence... You open your eyes to reveal you in a lavish bedroom you've never seen before, looks like a guest room

"Honestly. What were you doing?"