I'm thinking the CROW (Cryptic Roamers of Worlds, mostly evil and selfish) should have some sort of visible transformation once they fully sever themselves from the Flock (evil CROW group/home base)...
...so have Calypso! He's half CROW so that's why he doesn't ever fully change

My friend/sort of almost a friend at school (who's such a phenomenal artist it scares me) looked at him and was like..."so...what's up with his eye? Is that a blackout eye?"
Me: "uh, I didn't know it had name or anything--but yeah I guess :'D"
Her: "HMMMMM"
Me: *feeling very judged* "what???"
Her: "It's just...that's a VERY overused trope" *proceeds to flawlessly draw Sans on the board*
Me: ..............."oh"