When playing through Resident Evil 2 disc one for the first time, you witness a scene near the end of the adventure where Ada Wong is wounded by a gunshot and proceeds to tumble over the side of a somewhat ill-designed bridge. She is grabbed by Leon, who appears to do his best to save her before she plunges into the darkness below.
But is that what really happened?
Anyway it's the reason I think that the Ada in the blue coat in RE6 is a clone, if Ada could really kill all of Chris's men...being that cold hearted then she wouldn't of had a problem killing Leon but she saved him over and over again in RE2 and RE4. I think she loves him but because her work comes first and they both play on differen't sides she knows it would never works...I bet he thinks the exact same aswell.