Seen the series and I agree with you in the extent that he's a perv same and Slaanesh and her followers. I dunno though I was just discussing how alluring Slaanesh must be to space marines and the like since they have gone decades of centuries without the concept of pleasure or satisfaction in their lives. What with the whole unable to reproduce and ruined sex drive, I imagine the lure of her whims would be so uncanny to the space marine who beleived so fervently and was chewed up and spit out by the Imperium just like a husk. When Offered contentment, pleasure and ecstasy... he is offered a psychological reward for battle rather than continued survival... to me that is really hard to say no to once it's been given once.
Orchimaru was ... well simply put cliches wrapped almost a sexually frustrating persona; He was evil for evil's sake and really just wanted power. To me Slaanesh is like a really crazy girlfriend that you just wish you could quit but she knows all the ways to force you to let her back into your life *cough*sex*cough*. Their serpentine qualities are similar but in Japanesse culture it is honoring his cold blooded nature but in much literature primarily the medieval/christian based founding of the Imperium the snake represents temptation and seduction even though Orchi's mannerisms are similar I just think this was more a byproduct of trying to make the villain as eccentric as possible rather than believable.
It's a decent observation but i would say it took a bit of reaching to make only due to the poor nature of Orchi's character devel.
Simply put Orchi seduced Sasuke (sp?) by promising him power and showing him how weak he was in battle and then told all of his friends it was of his own free will
A champion of Slaanesh first and foremost wouldn't have cared if it was free will or not; But it would have offered an enemy "a gentle reprieve from the endless cycle of war ... in the arms of pleasure and satisfaction."

I always feel like I need to be scolded for talking about Slaanesh in public like this
lol.