Are Rickrolls parasites, or mimics?
The Rickroll
Conservation status: Least Concern
Classification: non-native, non-invasive
The Rickroll is an unusual meme with a very complex life cycle. It is perhaps because of this complex life cycle that it remains one of the most robust meme populations year after year.
The Rickroll's early life cycle is characterized by mimicry, as you suggest. The larval Rickroll will imitate the calls of other links in order to induce a click. This has allowed Rickrolls to reproduce for some time.
However, the life cycle of the Rickroll has a secondary stage induced by ecological saturation. When the environment becomes too full of Rickrolls, bloggers begin to assume that any link clicked is going to be a Rickroll rather than the promised content. The Rickroll's unique evolutionary strategy here is to induce the belief that a link Is a Rickroll. Curious bloggers will click to see if they are right, and even if the link is NOT a Rickroll, the Rickroll meme is able to reproduce successfully.
This unique aspect of the Rickroll plays a critical part in one tactic used by meme conservation experts to re-introduce critically endangered memes into the wild. You can read more about this effort here.