Endverse Cas was human. So it's not like he could have called upon his powers and tell the difference.
Do you realize how intimate that is. To be so used to and familiar to someones touch, that you instantly know it's not right. To be that intune with someone, that you recognize them under any circumstances?
Stuff like recognizing someone no matter what they look like, no matter what body they're wearing, no matter what time frame or universe they're in, is usually reserved for soul mates. It is as big a romantic trope as you can get. DESTIEL IS CANON AND ITS BEEN CANON FOR YEARS.
Credit to pondlifeforme and backwardsdestielandblueeyes for the pics!














