Is it possible to have sex with a character other than the sexy Psycho while running? I discovered that character interaction with the sexy Psycho and another with the lumberjack, which involves removing her top, but are there any similar actions with other characters?
Certain enemies change their appearance under specific conditions, like you menetioned for lumberjane is the shirt breaking, but those are just there to indicate that you have weakeded the enemy (not all enemies can be weakened, I'll leave the discovering which can be to you)
Being able to have sex with sexy psycho after defeating her is another separate matter - only she is currently fuckable, next in line is unholy nun