They contain...
A bit about how they first encounter one another in the beginning
Different sections that depict how they interact (which will differ mattering their personalities and histories, since that leads to different ways characters act around each other)
Just times they're together (including little nitpicky things that might be quite telling when looked at as a whole, in addition to official merchandise and artwork)
How their story ends
My opinions (which may or may not include comparisons to alternate pairings or me shooting down arguments against the pairing)
Cheesy things you can do in-game to prolong the romance outside of the story, mostly by putting them in the same battle party
Other game cameos (if applicable)
Shrine to Jet and Virginia (Wild ARMs 3)
Shrine to Stahn and Rutee (Tales of Destiny)