okay!
spoilers below here....
avert your eyes......
okay so as I said disclaimer that I don't read Korean and this isn't going to be exact or detailed, but basically what I gather is that Changgyeong becomes ill and Mokhwa ends up contacting his old trainer (and Mokhwa's old manager) to take a look at him. Changgyeong is super delighted when he wakes up to see the man he's been looking for all this time and reacts by kissing him...and you can pretty much guess Mokhwa's response from there (lots of tears, the poor bean).
Mokhwa ends up getting kicked from his apartment (presumably for not paying rent) and decides to go back to live with his family. He doesn't show up for swim practice so Changgyeong goes to look for him only to find movers in his home. He then takes off running, stopping anyone who resembles Mokhwa in search of him. When he finally finds him, he basically drags him back to his home and then after they have sex and he passes out, ties him up (lol) so he won't leave.
Changgyeong's old trainer shows up to the apartment again and basically tells Mokhwa (while Mokhwa is still tied up naked from the waist down on the bed lmao) that Changgyeong is like a human child and needs to be taught proper social etiquette. I /think/ Mokhwa is still jealous over how Changgyeong acts with his old trainer, so he takes off from the apartment again...only to get chased by Changgyeong. He chases him onto a bus and confesses his love right in front of a bus driver (lol) and then proceeds to tell Mokhwa "I love you" over and over again throughout the ride haha.
They stop off at the ocean and Changgyeong transforms and takes Mokhwa on an ocean ride. Mokhwa falls off his back and almost drowns, Changgyeong cries thinking he's dead. He, of course, isn't, and afterwards they go to a motel. Mokhwa starts feeling dizzy during sex and passes out from a cold. Changgyeong's old trainer picks them up and once at the apartment, Changgyeong and Mokhwa discuss how Mokhwa is going to stay at his place now.
Aaaand after that, there is another story with Changgyeong's old trainer (Manager Ji...I forgot his full name, sorry) and a human/killer whale that he's keeping at his place. I haven't bought those chapters yet.
He's not! He's a dolphin. He makes that face because that's how dolphins show their aggression / threaten others from encroaching on their territory. Changgyeong, I believe, was raised in captivity by the humans so he is more endeared to them. Rino was captured by the humans in a fishing net and was injured in the process, so he takes his revenge by performing minor crimes lol. (but in reality he's way more integrated into human lifestyle than Changgyeong is...not that he'd ever admit it) Basically, he thinks humans are lesser creatures so Changgyeong is a fool for liking them so much.
caved and bought most of the raws (here btw: https://www.lezhin.com/ko/comic/dolphin ). I don't know Korean but between the pictures and google translate, I pretty much get what's going on. If anyone wants spoilers, let me know~