[ THANKS............ at least his arm is safe, for now.

Unfortunately, at Xue Yang's question, Wei Wuxian is thinking the same thing. He hadn't thought about it like that before and has to give it a good think before he's able to respond, chewing over the details in his head. ]

I think he knew what he wanted me to do, his desire was so strong that it was conveyed without needing to say it. I'm not sure if the summoner needs a specific task in mind before they summon the spirit, or just a desire to be present for the spirit to absorb. But no, he called for me, but he didn't say "kill my entire family for me" afterwards.

I think a lot of this depends on the caster's intentions, and how badly they want their request fulfilled. That's the key part.