He's in love with her.
It hits him when he finds him laughing with her over something stupid Black*Star did. What was so funny, Crona can't remember exactly. Only that Maka is beside him, and her eyes are such a deep, rich green that he can't help but stare into them. Only that her laugh is wonderful and fills his heart with joy unopposed by any other emotion. Only that she is with him, and he is with her.
Crona catches himself thinking of her much more often after he realizes that he loves her. He thinks of how she makes him feel- warm and content, completely happy- and how she can help him deal with everything. She's saved his life so many times.
But he will never deserve Maka Albarn. No matter what he does, Crona will never deserve to be able to love her, or for her to love him. Maka is good, heroic, kind-hearted. Crona is corrupted, easily manipulated. He is broken, and he knows that it's all his fault that he's ended up like this.
Maka deserves more than him. Even so, Crona finds himself heartbroken when he sees her and Soul.
Yes, he knows that Soul and Maka deserve each other. They are weapon & meister, best friends, roommates, they simply go together, in a way that Crona knows he and Maka never can. It was inevitable, really. Besides, he can't be too angry. How many innocent human lives had Soul ever taken?
But it still pains him, after they begin dating. Heartache strikes him, flaring up through his heart and into his mind, as intense as Medusa's arrows, as maddening as the insanity that he feels threatening to take his mind every waking moment. Crona cannot bear to see them kiss, or hug, or hold hands, or even to look into each other's eyes. He's physically pained by it.
The madness closes in on his mind, further each day.
Six months after Soul and Maka began dating, Crona finds himself walking the streets of Death City with her. Under the streetlights, Maka's hair shines the color of honey, and her eyes sparkle.
"Crona, are you ever going to move out of Shibusen?" she asks, her tone light with serious undertones. "It can't be that great, living in a dungeon cell. There are some apartments around where Soul and I live, and- if you want to," Maka adds quickly, seeing the look of reluctance and fear on Crona's face, "- we could look into getting you a place."
Crona blushes and forces a weak smile on his face. "I-it's no p-problem, Maka! R-really!" he assures her, waving his hands in front of his face. "It's fine a-at Shibusen! Honestly. You d-don't have to worry yourself over m-me."
Maka doesn't look convinced, and Crona's terrified that she might protest. But before she can say anything, Ragnarok bursts out of Crona's back.
There's a sharp jolt of pain as Ragnarok exits his spine, but Crona's learned to block it out. He's more worried about what awful things his weapon might say than the hurt.
"What the hell, Crona?!" Ragnarok yells, beating his fists on his meister's head. "Of course that jail cell sucks ass! You're just too much of an idiot to get us outta that crappy place! Maka!" he screeches, raising his head to look at her. "Better get us an apartment, you fat cow! So don't listen to this fu-"
Ragnarok quickly retreats into Crona's spine before Maka's book can connect with him. The chop hits Crona instead, smashing into his skull with the full force of Maka's anger.
"Oh my god, Crona!" he hears Maka cry out through a haze of pain. He looks at her, and he's struck by what he sees. Maka looks sad. Regretful. Horrified. Worried.
All because of him.
And Crona doesn't know exactly what he's doing as he ducks his head away from her and mumbles, "It's okay, I gotta go," and he doesn't know why he runs away from her and through the alleys of Death City. He doesn't know where he's trying to go, except away from her- Maka and the worry and care he doesn't deserve and none of the love and affection he so desperately wants. Away from her voice, her hair, her eyes, away from Maka. He can't take it anymore. He can feel the madness closing in, every corner of his mind affected by the creeping insanity.
Crona runs away from the cure to his madness.
And somehow, he is aware of her presence, though he no longer knows how long he's been running or where he is or who he is. Even though Medusa is gone and so he has no one to go to, he runs from her. After a while, it occurs to him- perhaps he is no longer running from Maka, but, rather, the thought of her.
He does not know anymore.