Do you ever think how Series 5 is defined by Merlin seeing that vision of Camlann, of Mordred stabbing Arthur, of Arthur falling?
Much like how Morgana changes when the Cailleach tells her about Emrys, paired with her own vision of Camlann, Merlin changes when he is given a similar vision, similar knowledge.
Merlin is darker already after the 3 year time skip, but the entire series you see him slip into this version of himself that is hardly recognisable, even when you compare him to his characterisation in S4.
But it's that vision, the actions he takes with Mordred, how he behaves with Uther's spirit, with the Disir, with brainwashed!Gwen, with Gaius when he tries to prod at what Merlin has become, even with how he acts around Finna...
It's something that knocks me down every time I watch a bit of Series 5, any scene with Merlin feels like I'm watching a man at his very limit. Like he's so close to straight up murder I think.
Much like how Arthur says in S5Ep1, betraying their beliefs is what would destroy everything they've strived for.
And if you look at Ep5, Ep11, yeah, yeah that's exactly what happens with Merlin. He's so darkened by his destiny, so determined to do almost anything to protect and save Arthur, that he betrays himself.
And that ties into how Merlin is the light to Morgana's darkness. Where Merlin changes because of love and his will to do good overall, Morgana changes because of hatred and her will to do everything to succeed, even hunt her own - which includes her search for Emrys.
It's just !!!!! because I love how Merlin acts in Series 5. It's the little things too, like the way he puts on his jacket when sneaking out to meet with Finna, the way he's so smug when he says Mordred has beguiled them all, the way he stares at brainwashed!Gwen when she's about to accuse him, the way he snarls at Uther's spirit.
I love him, I love him so much, I could talk about Series 5 Merlin all day, he's just perfect!
