the core transfer wasn't "surgery without consent" tho? it wasn't informed consent - jc didn't know he was getting *wwx's core* - but he did absolutely consent to getting a core from bsr and didn't ask/care how.
In order for consent to be valid you cannot have obtained that consent by lying to the patient about material facts which you know would change their yes to a no. This is not a subjective standard I personally happen to have invented; the idea that deceit can vitiate an agreement is well established in law, and I would argue is also a pretty standard part of most people’s moral codes. That’s why, for example, misrepresentation is grounds to void a contract; if you lied to me about what I was buying, then I didn’t really agree to the sale, because I’m not buying what I agreed to buy.
In a medical contex lying can undermine the patient’s consent both legally and ethically, and that is in my opinion a much more serious problem than a broken contract. In a modern context, a physician can be charged with assault or sued for battery when treatment goes beyond or deviates significantly from what the patient consented to. In order for consent to be valid, the patient must have been properly informed. If consent isn’t informed, it isn’t consent, because if you don’t understand what you’re agreeing to or if you think you’re agreeing to a different procedure then you are not consenting to the thing that is actually happening to you.
Jiang Cheng, as you said, consented to go up a magical mountain so BSSR could restore his core. He did not consent to a dangerous experimental procedure performed by Wen Qing, which had a 50% chance of failure and would, even in a best case scenario, permanently disable his brother. Where the core came from was very relevant to Jiang Cheng, which is why Wei Wuxian lied to him about that in the first place. He knew that Jiang Cheng would not want his core, and he wanted to give his core to Jiang Cheng anyway. He lied about the nature of the treatment and its likely outcome, which is, as you suggested, the heart of informed consent, but it was not a careless omission. It was a deliberate attempt to get him to agree to the core transfer under false pretences. It wouldn’t be valid consent even if it was an honest misunderstanding, but I think it’s pretty relevant to the question of how Jiang Cheng feels about the whole mess that it wasn’t.
Regardless, medical consent isn’t a gotcha where you can lie about what the treatment entails, who will be performing it, and what the possible adverse outcomes are and then turn around and say the the patient got the result they wanted and the only bad thing that happened was someone they loved being maimed so it’s fine. That’s not how any kind of consent works. You have to understand what you’re agreeing to in order to agree to it, and if someone deliberately lies to you in order to compromise that understanding, they are compromising your consent as well.
