I guess this is my last ditch attempt to lay down the rationale behind my choice.
It is imperative to let Changfeng know that there are people here that are on her side. There are too many things that can go wrong if we don't:
- She might attempt escape, and get killed in the process. It is much better to go down fighting if you think that you are going to die either way.
- She might end her life. Even though this development is unlikely, given what we know of her character (her hate should carry her through the ordeal), there is a limit how much abuse a human can take if there is no hope.
- She might refuse to cooperate with her captors and provoke them - with foreseeable results. If she knows she is getting out soon, she can allow herself to stall the interrogators.
- She might get transferred and would not leave us a clue as to where, because she doesn't know anyone would be looking.
I think people have agreed about the importance of having everyone on the same page when devising a plan. Now that our plan is to speak with Changfeng about the events that transpired 3 years ago - and we would probably need to get her out of the prison first - don't you think it would be a good idea to update her on the current development, unless you want your carefully laid plans to be ruined?
If she is getting moved, it is not going to be a sea resort she ends up at - it will be a place which is equally well fortified, if not better. Political criminals were guarded way better than the ordinary ones at all times. I can think only of two reasons why she can be transferred elsewhere instead of being kept in the fortress or straight up murdered - she is either going to be executed publicly, or tortured for some sensitive information. In both cases she is likely to be guarded by people that are directly affiliated with the Empire, and thus have much more resources at their disposal that a single clandestine assassin group.
That is even excluding the possibility of her being outright killed. For example, if they are looking for the leader and Changfeng knows where she is, the captors would keep her alive, but if the leader is found, there would be no more use for Liu - this is just one example where time can be of the essence. If we knew she was kept there for two weeks, maybe we could afford to spend another one searching for clues, but she literally just arrived here. There is absolutely no telling what will happen the next day, not to mention after four or five more.
We have earned a certain amount of goodwill with Yu, saving his life, buying him out of his debt, and pandering to his anarchistic views and spiritual hobbies. If something happens to Liu because of our hesitation that I can't really justify, all of this is going to be for naught. And you can't even blame him, everyone would be royally pissed if their girlfriend was sold to slavery or tortured to death while they were dragged on a field trip by their leader.
As for D, once we get Yu inside the prison, it opens a vast sea of possibilities to us. Sure, his conversation with Liu will be supervised, and he is unlikely to say anything meaningful to her, nor get anything useful out of her in return. But he has a magical umbrella with him, and no one in their right mind would suspect it to be haunted. No one would - or even could - supervise a ghost. If Yu mentions something about not needing to be afraid of the next world or something similar to prepare Changfeng for the meeting with Xiaoqing, it opens up a way of communication with the prisoner. If there are clues at the site where the battle took place that can help us free her, Liu will give us its coordinates and spare us a week long trip back and forth. If there are remnants of the sect that can help break her out, she will provide us with the information necessary to get in touch with them. She might provide information about her leader if there is something that she needs to report. She might provide the number of the fighters the Society has, or the identity of Imperial spies within their ranks. Finally, if things are urgent, Xiaoqing can provide assistance in breaking Liu out by sucking the life essence out of guards. It's not like assassins have a priest with them. I wonder if she is corporeal enough to be able to toss Liu the keys from her cell. The personal ghost we got is just so awesome, I'd hate to see her potential go to waste.
There is a goldmine of information that you can make use of, waiting to be tapped right here, under your nose. To risk it for something that you aren't even sure what it is and spend a week blindly bumbling around the forest is just folly.