These two were set up as supporting characters for Booster Gold' s second series but after Johns/Katz left the title they barely showed up. As a result we missed the chance to see some great plotlines and interactions.
It seems incredible to think that they barely made an appearance since their relationship to each other was essential as their the leads ancestors. Daniel seemed to be okay with this while Rose was stunned by the news. Then we learn they've been dating off panel when we next see them? What about the conflict and pressure they'd feel towards getting together to ensure the Carter line continued? Sure it was hinted at Rose being attracted to him before they learned the truth but that's still quite a leap to make after meeting someone.
If I remember right they only came back a couple of times in the series, one of which was has seemingly been ignored. (*1) We never see Daniel being introduced to Michelle and Rose never shares panel time with her. Booster was living with Daniel when the series began but he states he's visiting during the Blackest Night tie in. The two never seemed to connect prior as Booster was disappointed in Daniel's disinterest in doing anything beyond being a slacker.
It feels especially disappointing that nothing was really done with Daniel after 52 where he helped save all of creation. There's no developments with him using the Supernova suit as a hero and even Skeets insight on Daniel potentially being traumatized from by being stuck in a time loop. Still Daniel could have made a good foil for Booster. While they shared some similarities as football players that missed their chance to make it big Daniel was more passive. He had no drive to make the effort to better himself and was stuck in a rut. While Boosters' football career ended due to his selfishness Daniels' ended because of an injury. His descendant can sell everything while he is almost the worst salesman at his job.
Rose on the other hand has ambition despite being a blogging reporter. Interestingly she's one of the few in the series that sees past the appearences and understands the illusion of hiding behind an image. Her own reasons for the slight change in her own image isn't as complex as having a secret identity to protect but she still understands insecurities. After having one meeting with Booster Gold she's sure there's more to him, something even other superheroes fail to notice despite working with him. While Booster is a good liar Daniel isn't which is amazing when you think of the history of the Time Masters.
The last time we see the two Rose is upset that Daniel is wasting time on video games instead of doing what she wants for a date. When a Black Lantern Ted Kord threatens Rose Supernova shows up but Daniel almost dies as a result. I'd be cool to see them at some point since they have yet to show up since DC relaunched--since New 52 that is.
*1 Remender' s fill in story became questionable canon when Booster found out he had a son. Jurgens didn't know if Remender had misunderstood his role as a fill in and admitted in an interview that reveal didn't fit in the series. Because if Booster knew he had a kid he'd want to find out the truth since it wasn't something he could forget. The two issues were never mentioned in the series and weren't collected in trade.