Secret, from the ask game, for Vespera and Rusty both
Vespera's past is shrouded in deep mystery, but it's mysterious, because of the circumstances behind her creation. Her name derives from a line of code called "VESP-Era1", which she's found is a "generation 1" of her line of creations. She's aware that she was made from Androsynth DNA that was stolen from a base in 2135(the timeline of the original Star Control game), but who created her, she may have taken a stab at looking into.
Her deepest secret that she never explains to her visitors(as few as they are) is that she is actually capable of reproduction. And she has a sample of another VESP-Era1 in her possession, she's too afraid to germinate it as of yet, because she wants to wait until there is a "Universal Calm". She just explains herself as having Androsynth characteristics, but since no one asks, her capability is kept secret.
Now for Rusty!
In his seven years of service to a demolition company, Rusty has met a number of alien races, some that even gave him "The Glare". A specific look in one's eye when they look a Melnorme in the eye is a sign of romantic interest. And one instance of someone who was interested in Rusty also happened to be someone who wanted to be taught about love before he passed.
This individual was a Thraddash named Bdunk, who had a mechanical hand due to an accident. In his final days, he wanted Rusty to teach him about romance, and that teaching led to a short-lived, but worthwhile romance between the two.. When Bdunk finally passed, his mechanical hand was given to Rusty as a reminder of the fact that he opened someone's eyes about something he never really knew about.
Rusty still has this mechanical hand and he does still miss Bdunk.