(Oh-oh! Thought/idea! Mermare's mate caught in a fisherman's net! Mate gets hurt before he gets there?)
First of all the damn fisherman who did it an accident or not just signed a death warrant.
The thing is that while the net might not hurt more than a rope burns, its the process of being hauled up onto the boat and physical injury in the process of binding you up or getting you in a tank when you were struggling and maybe you were too hurt to try fighting back.
Either way he was moving as fast as he could but was a bit too far away to keep you from being hauled up and it’s a full fishing boat on a dry surface you didn’t have much leverage in the situation.
But when a fully grown deepwater merfolk jets out of the water and slams into the side of the boat to stop whatever was happening and try to break the damn thing in half? Then there were some issues for the fishermen.
See, your Mares mate. Your smaller than he is and he adores you so he’s going to protect you but if you're in serious danger like I’ve said before he falls on instinctual actions and rage.
Grasping at the boat and pulling it down towards him not as rough as he would like to because you're still on board but the moment he has you in his grasp he’s clutching you to his chest with a guttural growl directed towards the humans before he dives back into the water.
The damage he had done to the boat messed with the engines so the humans were stuck in terror waiting for help that was miles and miles away.
In the meantime, Mare quickly looks you over for injuries. Takes note of just how injured you are, finds a dense patch of seaweed, presses a kiss to your head and tells you to stay right there. He’ll be back he just has to take care of something… He mostly doesn't want you to be scared by what he’s planning on doing.
After making sure you're alright to be left alone for a few minutes he stalks back towards the boat. Circling it and putting on a show of flashing his gigantic tail out of the water. Or a massive fin just to rile them up. He might bump the boat a few times to really scare them before raising his tail out of the water and slamming it right down the middle of the boat and snapping it in half like a twig.
With a now quickly sinking boat and a good handful of people swimming away from the wreck so they aren’t pulled under as well, Mare is going to have some fun. Picking them off one by one, biting their heads off and leaving them but eating their bodies in a single swallow. Leaving everyone’s head to float as their blood fills the water around the now alone fisherman that caught you originally.
This is the one that hurt you and oh no no no a meal won’t be made of him. This one deserves the special treatment of course. He leaves the fisherman in his own fear for what seems like forever. Pulling him down a few yards on occasion and watching him struggle to get back to the surface. Fucking with him just because he can before grabbing him and taking off to where you are.
He does let him go back to the surface for a few seconds here and there. Mare needs this one alive after all.
What happens next depends all on you. Are you a meat-eating type of merfolk? If so Mare will wrap his hand behind you to support you and offer him to you as a meal. Ensuring that he can’t move or fight back or hurt you while you eat. Just watching you while you do with a tender gaze which does not fit this scenario but your meat eaters it’s natural.
If your not a meat eater or don’t want to see said human again Mare will nod without judgment and probably just give the human off to Anti. Knowing that the glitch will eat him alive and slowly all for fun.
Afterward, Mare is so gentle and sweet. Wanting to carry you everywhere and catch your food and anything else you want (even a bit after your back to full health) so very cuddly keeping you to himself during this time because you're more vulnerable than normal and he just wants to keep you safe.
Mare is a sweet boy of course but if his loved ones are in danger he holds no mercy for anyone who’s to blame.