It's almost worse that John initially tries to take responsibility for having gone too far. It'd be within his rights to regret it, Martin thinks, and he looks away as bitter shame starts to creep over him. John stops himself, and there's an achingly long span of seconds wherein Martin is sure he's about to be let down gently.

But then John rephrases it, and while it doesn't totally allay Martin's anxieties, it does pull him back with a shocked stare, shame momentarily cut off by astonishment as John tells him he was perfect. His concerns sound more reasonable than anything close to rejection, though Martin's own tendency toward insecurity is determined to see it that way — but perfect?

Maybe it was just colloquialism. Or an affectionate remark that slipped out, meant for the other Martin, the experienced Martin. That makes more sense, and it isn't long before it takes root as the only truth Martin can accept, and his expression slackens a bit as he looks down at their hands.

"I..." He frowns tightly, already feeling the threat of potential tears, angrily trying to stave them off. Christ, not after all that, after he already pulled John out of a depressive mire. He swallows and says, "I don't know how to do this, I... I don't know how to be that Martin. I want to—!"

He looks up quickly, lest he be misinterpreted, finding John's eyes, his own darting nervously between them. "God, I want to. I just—I'm scared I'll get it wrong, or... or I won't be what you want, and—"

He can't maintain eye contact, and he looks back down, back at his hand still clasped in John's, wondering if he ought to sever that contact as well. "This isn't mine," he says, soft and far more desolate than he'd like.