In mythology, sirens are usually sea creatures, and this is just my opinion, I think the theme of this drawing would be better portrayed if there is at least a hint of aquatic blue in it. Because as it stands I never would have guessed that the drawing is a siren unless someone explicitly told me that it's a siren. But I do like the pose of the octopus, like the way it weaves and blend in with the siren. and the sucker on the octopus seems pretty spot on.