1. It all starts when Missandei gives Grey Worm lessons in the common tongue, and they start to form a bond.
2. They begin to share many subtle glances.
3. As well as moments of extremely intimate eye contact, when left alone.
4. Really, they sneak stares in whenever they can.
5. Though not SO subtle, as anyone remotely close to either of them catches on right away.
6. And they respectively get defensive each time.
7. It's clear that they mean a lot to the other person.
8. They can be really honest with each other.
9. And they feel free to ask each other anything.
10. Like any two people with intense crushes, they have tendencies to be SUPER awkward around each other.
11. But then they also see right through each other in a way that restores your faith more than anything in Game of Thrones.
This happened in the episode where Prince Oberyn died, which, in retrospect, was so needed.