Recently I've been trying to pin down the precise reason why I don't like Martin Blackwood (aside from the fact i find him annoying) and I think I've come to a realization of sorts.
It's not that I think he's badly written. (As I've stated in my previous posts, in my opinion he's quite well portrayed; by that i mean he makes the decisions i think a person like him would make. While his actions aren't often "the best" or however you want to phrase it, they can be understood if you tried to look at them from his point of view).
I dislike him because there's nothing unique to him.
Let me put it this way. He's a shy guy with an embarrassing crush, family issues and depression. He also expresses himself in that cartoonish manner usually associated with bubbly, insecure characters. But he doesn't tell a unique story.
If you didn't already like him for his anxious personality, then his backstory (and development) don't really give you any further reasons. He fits into the classic "shy character who's actually smart and cunning" archetype. He likes all the stereotypical softie things - poetry, tea, idealized romance, cozy sweaters (that part might be fanon tho), he's nice to animals and insects, and the whole revolutionary part about his character (that everyone praises him for) is that he's actually manipulative and hides it well.
His whole character seems to be built on a mix of those softie traits and trauma. Even his Lonely arc is just a metaphor for heavy depression. He's never affected by the horrors (beyond the impact it had on his mental condotion - duh) despite being the focus of a fear-apocalypse themed season.
Also it feels like his whole role, whatever it might've otherwise been, was changed in s5 to become an anchor for Jon to latch onto. His whole thing is that he's "still human" and can pull Jon back whenever he's being "too monstrous". Which is WEIRD, because not a season earlier he became a full-fledged avatar of the Lonely, even if it was partially on his own terms. He doesn't really feel like a hero of a horror fiction podcast, just an angsty queer romance. His biggest appeal is that he's relatable.