What is the nicknames for Izzie and Alex?

They are best known as 'Lexzie'. Hope this helped. =]

What 你 mean - nickname, something like McDreamy and etc. 或者 nicknames of them like couple?

I don't really use a nickname for them~ I just say Alex/Izzie but I think that the most known one is Lexzzie~ 你 can come up with many combinations though.