>>222670716If you look at Wylad's human form and compare it with his apostle form, it suggests that behelits grant you a form based on a turning point in your life where if you had the apostle form before your turning point, the turning point wouldn't have happened.
Griffith would've escaped being imprisoned and tortured had he had wings and could fly away like a bird after his romp with the princess. The bird form also represents his dream to sore above common men.
Void was a person with below average intellect who aspired to be a scholar. He was mocked for being stupid, lecherous, and a leper so he became a form with no eyes and thus no lust, no body and thus no ability to even copulate, and a big brain because he was stupid before.
Slan was probably an ugly, obese woman who aspired to be beautiful and charming. She never had sex or the ability to attract any man, so her new form was the opposite.
Conrad suffered from starvation, became a beggar, and was eventually killed by disease so he became an obese plague spreader who never needs to to open his hands to beg anymore.
Ubik was an honest man who got swindled and lost his business, wife, and family so he became a spreader of lies and chaos in the form of a starfish because starfishes are emotionless animals that reproduce asexually and have no need for families or relationships.