Deep One Hybrids

When a Deep One and human mate—as is the Deep Ones' way—the child is born human. It is not until puberty that they begin the change into a Deep One. This transformation takes years, or even decades, so during this time they are referred to as "hybrids".

In the RPG...

Deep One Hybrids are another staple of the Call of Cthulhu beastiary, most likely because the majority can still pass as human, so can fit into any number of scenarios... though usually ones set in seaside locales. Their stats are also well within human range, which is another reason they are so "versatile". As mentioned above, change begins with puberty. According to the Malleus Monstrorum, the transformation will complete—officially becoming a Deep One—somewhere between the ages of 20-40. It is also stated that 10% never fully make the change, and 10% of those never change at all, though they still carry the genes, which will be passed on to any children. 

    The older Malleus Monstrorum gave Deep One Hybrids the same stats as an investigator, but the 7e edition has changed them slightly, with POW being the only one to stay the same. STR, CON, and DEX have been changed to 2D6+6, which gives a higher average as well as a higher minimum value. Increasing STR and CON makes sense, but I'm not sure why they would be more dextrous. If anything, you would think it would be lower. SIZ on the other hand has been made into 3D6, which lowers the average and minimum below that of a regular human. Why would they be small? Especially since they're changing into a Deep One, which has higher SIZ stats than a human. This change makes absolutely no sense to me. This means that 9% of all Hybrids are smaller than your average dog.

In a video game...

Deep One hybrids were the primary antagonists of the video game Call of Cthulhu: Dark Corners of the Earth—at least in the first half of the game. They're perfect for the role because while appearing as just ugly or deformed humans, they're generally aware of their heritage and will do what is necessary to keep that secret secret.

In a film...

Because The Shadow over Innsmouth is one of Lovecraft's most popular stories, it has therefore become one of his most adapted ones, so Deep One Hybrids have already graced the screen many times. Regardless, they are such a versatile villain that I'm sure there are many untold stories waiting to be made.