Kevin
Water Affinity
Strengths: Kevin is a skilled swimmer and though he cannot breathe underwater, has the ability to hold his breath for far longer than any normal human could hope to safely achieve. He also holds a small degree of control of water, limited to giving himself a boost of swimming speed or being able to direct a gush at his intended target. As long as Kevin is in or near water, he is stronger, faster, and more agile.
Strengths: Kevin's sight, hearing, scent, taste, and touch are sharper than the norm. He sports an extra pair of eyelids that enable him to see through the murkiest depths. Hearing is easily his weakest sense, better than a human's, but nothing special. He can track a scent even into water, that is where taste and touch come in. Taste and touch are linked, Kevin can feel the slightest vibrations while underwater and even taste through his skin.
Camouflage
Strengths: Kevin can blend in against rocks, mud, and water. He is an ambush predator, laying in wait.
Weaknesses: This does not extend to his clothes and is therefore useless unless Kevin wishes to go around naked.
Weaknesses: Proportionate to his elegance and ability in the water, Kevin is clumsy as heck on land. He tires and weakens easily if away from a source of water for too long, this goes as far as becoming physically ill if he doesn't bathe once a day. He dehydrates very easily and needs to drink fresh bottled water often. While he can use it for bathing, ingesting tap water will disagree with him.
Weaknesses: All of Kevin's senses work best in an aquatic environment. His sight is better suited for seeing underwater and he is sensitive to bright lights. Tracking via scent or taste can be easily muddled by the introduction of an overpowering new agent such as blood - which can send him into a frenzy. His sense of touch is not nearly as strong on land as in is in water.
Enhanced Senses
And of course a minor weakness to iron, like all fae related creatures.