dedicated to the relationship between a teacher and a student.

Orochimaru was Anko’s former sensei, she respected him as if he were a god. That’s why she felt really hurt when she found out he was only using her as a test subject. During her time with him Anko was branded with Orochimaru's Cursed Seal of Heaven. Orochimaru supposedly rejected Anko as a subordinate, believing she did not have the lust for power or vengeance needed to fuel the Cursed Seal. Orochimaru lost interest in her, though he believes there is some value in letting her live. During her time with Orochimaru, Anko learned several of his techniques, such as the ability to summon snakes.
When they meet again in The Chuunin exams she tries to kill him by using Sōjasōsai no Jutsu, a technique that would kill them both. My theory is that Anko can’t live with him, but can’t live without him either, that’s why she wanted to die alongside him. Obviously she fails to do so and feels even more worthless when Orochimaru tells her about what he’s planning. She feels jealousy and he can easily see it in her eyes.
So if you enjoy pairings that actually have a story... a past then this is the place for you.