A brief background is that they are both gods. The smaller, Dimitri, was initially sent to kill Marcus because he's an exiled god. Marcus kicked Dimitri's ass and, being the nice guy that he is, actually nursed Dimitri back to health afterwards since the gods wouldn't take back a failure.

Long story short, they fell in love, but in order to protect Dimitri from his own god headhunters, Marcus got him a potion that would alter his physical race. He's still a god, but no one would recognize him as the elf he used to be!

Now Marc's trying to quickly get him into the water in case the sudden arrival of gills causes Dimitri's lungs to shut down for a time.

God fish! God fish! Love me some god fish!