Ohhhh man this is a hilarious scenario to imagine LOL this is like a tbal spin-off episode. First off I can see Aether & Xiao passing A-Qing off to Venti for a day (as they already did). He would have a very fun time with Venti (maybe a little too much fun) but Venti would make sure all his needs were met, talk to him constantly, make him laugh and sing him a lullaby, the whole 9 yards. Venti's got a soft spot for orphans. Gentle parenting Venti!

Zhongli.... oh boy. I think he would be a well-intentioned parent but as I mentioned, I could see him briefly forgetting about A-Qing while he goes off to brew 6 hour tea and take a long stroll through the harbor. The man has no sense of urgency. He would forget the immediate and constant needs that babies have and be like "Ah yes... I hadn't considered I needed to change his diaper." Forgetful as he is, he would know how to do all of those things. I can also see him taking A-Qing with him in a stroller to listen to a story at Third Round Knockout and giving A-Qing a complex explanation of historical events. Beneath the tough love (and maybe strictness!), he would dote on him a bit in a grandfatherly way.

Now I would not leave any baby with Ei, period LOL. I feel like Ei would be very uncomfortable and unsure of how to behave in front of a small child, I can imagine her speaking to A-Qing in full formal sentences as if expecting him to respond like a full fledged adult and ultimately being baffled when remembering he's a literal BABY. A-Qing would be afraid of her and she would panic immediately upon seeing him cry. I don't think she even knows what a diaper is. I give her 5 minutes tops before she's calling Miko for help and asking her to take him off her hands.

Nahida would have all the knowledge of how to care for a child, but perhaps none of the practical experience since the world is still so new to her and she's technically a young god herself. Nevertheless I think A-Qing would have a very calm and magical day with Nahida, she would play games with him, introduce him to the Aranara, and observe him meticulously with fascination. I'm picturing them sitting on the floor and coloring together in the forest with their aranara friends.

Now, all of the Archons taking care of A-Qing together? That would be a disaster. They'd all have different opinions of his needs, Venti and Ei would be passive aggressively bickering, Zhongli would be trying to make them all come to an agreement to resolve the situation, a mountain range would go flying at some point, and Nahida would probably sneak off with A-Qing before they all realized he was even missing.

This was such a long reply but I had fun thinking about it, thanks for asking & for reading the fic!