Al-Haitham had no idea how to communicate affection. So, he infodumped.

"Did you know that most cultures in Teyvat use the Sumerian script for numbers?" He says casually, staring you down with an uncanny amount of eye contact.

"It actually originated from King Deshret's kingdom," he adds for good measure, praying you did not, in fact, know such a basic fact about Teyvat's linguistics.