Lapis, Peridot, and Sharky are in a polygamous relationship. They all seem to care about each other very much. They could possibly be the only polygamous relationship in the town, and often times other characters judge them.
They are equal to each other as a healthy polygamy is but they all have complex feelings towards each other.
Sharky and Lapis have a very strong bond because they both have mental issues with anxiety and stress. They are sometimes toxic together, suggesting horrible things to each other for relief from mental pain. (Ex. They have cut themselves together, Sharky suggested heroin to Lapis since it might not be as bad for her since she is an alien.) Peridot usually steps in during the worst times, but respects their strong connection with each other. Sharky also would like Lapis to get help for her PTSD, and worries about her, often making her own stress worse.
Sharky loves Lapis and Peridot both but often worries about trying to spend equal time with each of them, and worries about ignoring one or the other by accident. Peridot tries to reassure her about this, since they all know deep down that they love each other the same.
Peridot does not have too many issues, other than being a little protective of the both of them, especially Sharky because she is more mortal.
Peridot is shown to be very protective of Sharky and Lapis. In Back Off my Girls!, she becomes enraged when several tree friends insult them online.
Sharky generally helps out Lapis and Peridot when they are unaware of Earth traditions as seen in Christmas What?.