Ling Qi knew that people could break from their most fundamental urges.
This line is interesting to me, and I think it's the guidepost for each of the options.
[] Cai Renxiang
Cai Renxiang is the individual we have the highest Bond with, which means our Domain is most obviously in play. We've spent a fair amount of time with her, and we know some of her scars, both from her own words and the words of Lin Hai. On the other hand, she's borderline artificially difficult to engage with. Some of her underlying urges, like being pure, free from flaw, capable, etc like her mother is/wants/needs/demands she be could make it harder to reach out. That really just makes it more interesting though.
Maybe we could end up even convincing her to try reconnecting with Lin Hai!
[] Gan Guangli
In-character, we don't actually know him all that well. Out of character, we know that his backstory isn't... wholly different from Ling Qi's. It's been implied Gan Guangli's father was a soldier who got crippled, was not cared for by society, and made his misery his son's, before Gan Guangli left that life behind to be by Cai Renxiang's side. There's definite parallels with Ling Qi's experience, enough I think it's plausible for Ling Qi to pick up the threads on the fly and have the two of them resonate.
[] Meng Dan
This would be the last one I choose. We don't know a whole lot about him, and what we do know doesn't obviously jive with a common theme or experience with real narrative weight. Might just be my limited imagination in play and I'm missing something, though.
[] Xia Lin
Here's where the "people could break from their most fundamental urges" line catches my interest most. Xia Lin and Ling Qi's thing they have in common is their shared core motivations to advance and grow, never stopping. Now, the reason that's interesting is because that same fundamental urge is also core to Ling Qi's current, yes it still exists, Heart Demon. It really hasn't been consistently explored. This is potentially a really good narrative opportunity to give the Heart Demon some more meat, while exploring the contours of Ling Qi and Xia Lin's shared values.
