What do you mean? Like I said he's body was sealed so now he needs a body to gain a physical form and anko is perfect for that. His chakra may just take over any moment now.
Ok, lets say you have two bottles. Let that represent Sasuke and Anko.
Then lets say a hole is made in the bottles of the exact same size, shape and location on the bottles. Let that represent the Curse Marks.
Now lets say you pour water in one of the bottles. The water represents Orochimaru. The bottle with the water in it is Sasuke. In order to stop the water from leaking out, you put some tape over the hole. The tape is the chakra that stops Orochimaru(the water) from escaping from(leaking out) Sasuke's body(the bottle) through the Curse Mark(the hole).
Now lets say you put tape on the other empty bottle, which is Anko. Its the same situation, just like how one bottle is holding back the water but the other isnt, Sasuke has Oro inside him to hold back, but Anko doesnt, thus being like an empty bottle.
Now lets say the tape on the first bottle wears off and falls off. The water would come gushing out. This is what happened with Sasuke. His chakra that was blocking Oro from leaving his body through the Curse Mark wore out, so Oro got out.
Now theres the second bottle. Its tape can wear out too and then fall off. But, since its empty, nothing comes out since nothing was in it to begin with. Its the same with Anko. Even though she has the same Curse Mark and has chakra supressing it the same way, Oro cant come out since he was never in her to begin with.
