The one instance of romance in my stories so far (save the story in which I can't decide who should marry whom... <grin> or perhaps they're all siblings and NOBODY will get married. <evil writer laugh>): 
Skye is passionate, vivacious, and compassionate. 
Lukas is reserved, calm, slightly sarcastic/cynical, and very professional -- but passionate in his own way about the things he cares about. 
Skye is a scientist with a heart for the outcasts. As a child, the orphan Lukas was crippled in a carriage accident, nearly causing his and his disabled toddler sister's starvation. However, Skye stumbled across the child one day and took her in. She gave Lukas technology to allow him to walk again. 
Over many circumstances, they ended up falling in love when they were old enough. They planned to marry, but Lukas was tragically killed when protecting Skye's lab from a burglary. Skye had previously left the city for her own protection. A few days after the death of Lukas, when Skye was supposed to return, it was discovered that she had left the country completely after hearing what had happened. 
I need to tweak everybody's ages in this story to make everything make sense... but the idea is that Skye is a year older than Lukas; Meadow (the sister) is about five to ten years younger than Lukas and about the same age (within a couple years) of the main characters Krystal & Evander (twins). 

 Confusing, eh? 
And it doesn't end as tragically as it sounds...