In the Harley Quinn TV series, many have assumed Poison Ivy is Harley's most important ally. It's understandable to infer as much, given Ivy helped her emancipate herself from the Joker's toxic bubble. In fact, this led to romance blossoming between the two, to the point it seems like they're soulmates who'll fight through their flaws in the name of true love.
Source：https://www.cbr.com/harley-quinn-king-shark-important-ally/
