Sherlock:
Yours: Sweetie or love.
His: Sherl, sweetie or cookie.
John:
Yours: Darling, love or gorgeous.
His: Doctor, Hamish or handsome.
Moriarty:
Yours: Beautiful or babe.
His: King, Jimmy or baby.
Greg:
Yours: Honey or sweetie.
His: Graham, babe or sweetie pie.
Mycroft:
Yours: Darling or love.
His: Myke, sweetie or honey.