The two have never met. Zarya is not part of Overwatch and Mei was in cryo sleep the past 9 years. Zarya is a former athlete who gave up on her dreams to serve Russia during the Omnic Crisis. Mei was a member of the Overwatch eco-team in Antartica. When her team was low on supplies they put themselves into cryo-sleep. Mei was the only survivor waking a decade later.
Zarya's barrier is typically very helpful to Mei during the game. Mei can't block very well against group, so the bubble can hold off enemies for a couple of seconds. Given that Mei is targeted by many, Zarya would have to keep putting the bubble on her. This helps Zarya charge up her canon faster. It also helps Mei get closer to they enemy team. Zarya's barrier can also help protect Mei once her blockade goes down, as most wait for her to get out of it and make her an easy target.
Their ultimate's also provide the same function. Zarya's graviton canon will cause players to be pulled in one spot and make it easier for other players to take them out. Mei's is similar, only she freezes members of the other team in one spot, making head shots easier for the other players and Mei.
Fans tend to ship the two based on them both being associated with cold climates. Zarya Russia and Mei Antartica. Fans will often depict the two in activities that involve snow.
- Mei – “Zarya? How can you even pick up all that weight?”
- Zarya – “I lift as well as I lift because it cannot be avoided.”
- Mei – “Zarya? I don't understand how you can fight in the cold wearing so little.”
- Zarya – “I'll tell you my secret if you give me your coat.”
- Mei is 31, while Zarya is 28