Basically a reunion of old friends/childhood friends/lovers/rivals/enemies in BL :)
This list ranges from the encounter being the basis for the start of romance to the encounter happening in the middle of the story because the angst and tension is too much and you gotta separate before you know who you truly love T.T (mostly the former though).
Peep at PT. 2 of the list:
http://www.mangago.me/home/mangalist/821542/ 
