You were only meant to keep Irene Belserion's cell. That's what Rung asked you to do. And the first days, it's what you did.
She was pregnant. Of some weeks. But more importantly... She's slowly turning into a dragon. Her skin was crumbling and falling, revealing dragon's scales. But weirdly... She was still beautiful to you. But you hided it. Acting as the cold guard you should be.
One day, as you came to give her food, she raised her head, revealing longer teeths and bigger eyes before saying her first words. "Could you... Eat with me?"
And you did. Today, the day after and weeks after weeks. You swore it'll be the last time... But you never stopped. You bonded together. She wasn't the monster everyone made her to be just like you weren't the cold guard you acted like.
And what should have happened...
Instead of staying outside her cell, you spent time inside. Soft kisses, promises in the dark, dreams admission while holding hands even if she already had two wings. You imagined yourself leaving together, find somewhere peaceful and educate Erza together.
And finally, one day... Her transformation ended. And she broke out, killing Rung and taking you with her. Your eyes kissed goodbye Fiore with a last gaze before you landed somewhere far from everything.
Irene was trapped in her dragon form... But you swore.
You'll save her.
Just like she did.