From what i've read Darkside Chronicles will explore Leons background and why he became the person he is, with Krausers appearance it would seem were getting an insight into what happened to Leon after RE2 but before RE4.
I CAN'T WAIT! as there is little to no backstory to Leon, he gets mentioned in other RE titles but as for his actual activites we have practically NOTHING to go on.
The only information ive managed to ind out about Leon is that his family was heavily involved in crime and were killed which made him enrole in the police and a lighter he carries was his fathers.
He broke up with his girlfriend just before leaving to join the R.P.D and arrived so late at Raccoon city because he got drunk because of the break up and was running late.
After RE2 he worked for an anti Umbrella persuit and investigation team and then ended up going to save Ashley Graham (even if alot of us wish he didnt
)
There are some pretty big gaps that need filling in Leons story and it looks like were going to get some answers!