Orochimaru's Mansion - (dub) 139 : Terror!

regarding the curse mark? An analysis of the Sound Four’s role in this episode? Hoe4Sasuke - Fanfiction.net

This episode highlights that Orochimaru’s power comes at the cost of one's humanity, body, and sanity. (Dub) 139 : Terror! Orochimaru's Mansion

It shows how Orochimaru feeds on the "misery" and ambition of others to sustain his own ego and immortality. regarding the curse mark

It sets up the thematic contrast between Sasuke’s desperate, lonely path of darkness and the bonds Naruto is trying to save him with. (Dub) 139 : Terror! Orochimaru's Mansion