A lot of you guys have already read a bunch of stuff from the actual official website, but actually one of the things in Overwatch that reveals the MOST about the characters are the voice interactions. Here are some things you can find out about them:

• Mcree is Reaper’s student/apprentice
  
• Reaper believes his current state is Mercys fault
• Zarya doesn’t like Genji and distrusts him
• Pharah has some kind of grudge with her mother, either out of spite for not spending time with her, or perhaps because she didn’t treat her well.
• D.Va and Lucio are fans of each other
• Reinhardt is ALSO a fan of D.Va
• D. Va on turn, is a fan of Mei’s blog/journal.
• Despite knowing that it is Genji, Hanzo refuses to accept Genji as his brother, and dislikes him
• Junkrat has some kind of amazing treasure and Hanzo/Reaper question him about it, trying to get some info out of him.
• Mei and Mercy knew each other before Mei went into cryostasis.
• Also according to Mei, Mercy hasn’t aged at all