I know "What happened to Mean Gills?" was an oorp joke not even made in the Life Series but I'm incorporating it into my character analysis anyways because it is so indicative of one of the most fascinating character traits of Martyn to me.
That being, Martyn always wants people to be simultaneously stable and disposable in his life.
"What happened to Mean Gills?" you happened to Mean Gills, Martyn. You poured a bucket of lava on Scott and stabbed him in the back. You killed him, before what was meant to be a fair fight, and then in victory you proclaimed to the world that allegiances don't matter. That's what happened to Mean Gills.
Martyn often talks about people like they're disposable, he claims to have no issue with using and betraying people, with lying to them, because his survival and victory is all that matters. And to a point this is how he treats people. Martyn will lie to the people who trust him, Martyn will stab them in the back, Martyn will do what it takes to survive, because Martyn is a survivor.
But Martyn is a lot more attached to people than he likes to admit- His King, His Mean Gill, His Big Dog, His, His, His, Martyn is deeply attached to his people, both possessively and protectively, more dependent on them than he likes to admit. There's a reason he keeps lingering, keeps getting drawn back to the same people, he cares about them, whether he'll often admit it outright or not.
I have a lot of sympathy for Martyn being someone who I think is torn between the very human desire for survival and independence and the equally human desire for connection and stability. I have a lot of sympathy for the way Martyn breaks his own heart over and over just to feel like he's free and capable enough to do so even though he loses so much in the process.
But this is a behavior pattern that impacts other people too, and a person is fundamentally not an object to pick up and drop as is comfortable. Martyn cannot have his cake and eat it too, he cannot betray and lie to people over and over and still expect them to be His Person, a fact Martyn often struggles to internalize. His own connection draws him back to people he's hurt in the past and it's hard for him when they have walls up now even though he did this.
(interestingly, i think mean gills might be an exception to the "you can't have your cake and eat it too" rule to an extent- scott isn't naive enough to trust martyn, but he's often very okay with being treated like an asset by people he loves. scott has a very special brand of self dehumanization where he'll spend seasons carving off pieces of himself to give to his partners, calculating how much to give until it's more economic to just die for them. so like. martyn could honestly probably just grab onto scott again and they'd be back like martyn never stabbed him in the back. but despite the fact that i think scott specifically would probably be remarkably tolerant of martyn's more destructive relationship habits, i still think "what happened to mean gills?" is a good showcase of martyn's view on things)
Anyways yeah I just think Martyn is fascinating he is so destructive to himself and others and it makes me so sad.