One of the episodes I was considering is "Eyes"
It's from season one, and features a compelling performance from Michael O'Hare.... and it gets even more into his background. We see more into Ivanova's history. And there's a nice little humor sidebar with the bit about Garibaldi building his motorcycle, with Lennier's help.
And since we're in the DS9 forum, it also has a nice little performance from one of Trek's most chameleon-like actors, Jeffrey Combs, in a decidedly more sympathetic role.