Malec is the fan made couple name for Alec Lightwood and Magnus Bane
Magnus, in talking about siblings who are attracted to each other, says he "once knew a couple in Ancient Egypt . . ." This is likely a reference to Cleopatra, whose famous romances may have included more than one sibling, most famously (and confirmed) her brother, whom she married.
Because Constantin Film does not own the rights to The Bane Chronicles, the mention of Imasu was technically not allowed.