It really depends on both the tone of canon and what you consider "crackfic".

If you're writing them both as penguins or girlscout cookies or something, then it's probably better not to without a concrete request. If your definition of "crack" is much broader, you might be okay.

If it's Venom or Deadpool or something, being turned into a girlscout cookie is significantly less weird than some of the shit that happened in the comics.