Looking at the orthopedic implications of being fused with an animal with a skeleton made entirely of cartilage - as the bones converted to cartilage, any sort of structural stability would go out the window.
Looking at combining human and shark skulls - both a shark's jaws are disconnected from the skull, allowing them to push them outwards and giving them a wider bite. In the 2/4 body sketch in the corner I incorporatede the 'lateral line', an organ of sorts on sharks that is very sensitive to vibrations in the water. Not much use on land, but neither are cartiliginous bones.
Just a quick sketch of a shark skeleton to get a feel for it. Apologies for the ink on the next page showing through, not much I can do about that.
And some Photoshop doodles. I'm struggling with silhouettes as it's not something I've tried before. Also more skeletal studies, and I learnt that sharks have their brains in front of their eyes. With a human-sized brain this has the potential to be very awkward indeed, so I migrated the brain forward to see how it looks. I'm not certain, but I'll hang onto the idea for now to see if it goes anywhere.
I also deliberately kept my glasses on all the facial sketches - I want to show that yes, even as my entire bodyt collapses I am still me, and small props like those help with that.