HAHA I COULD WRITE A WHOLE DISSERTATION ABOUT WHY I’M ABOARD THIS AWFUL, AWFUL SHIP BUT OH WELL:
1) Arthur: “I had no idea you were so keen to die for me.” Merlin: “Trust me, I can hardly believe it myself.”
2) You are but two sides of the same coin. One cannot truly hate that which makes it whole.
3) That thing that they do where they have sex but only with their eyes.
4) Pretty much 85% of the episodes will make you ship them. My favorite Merthur episodes are The Labyrinth of Gedref, The Poisoned Chalice, The Wicked Day, The Darkest Hour II, The Coming of Arthur II, The Moment of Truth, and The Last Dragonlord.
5) Progression. Arthur went from ‘but father i don’t need a manservant look he’s AN IDIOT. yano merlin we coulda been friends if you weren’t the way you were and i wasn’t the way i am’ to 'you’re the only friend i have and i couldn’t bear to lose you.’
*bonus 6) Merthur fanfiction is the best fanfiction in the whole entire universe and I’ve been reading fic since I was 11.