The Mass Effect universe and its characters belong to Bioware, though Kaylin Shepard is mine.

This happens right after the confrontation with Udina on the Citadel.

"My Immortal" by Evanescence

I'm so tired of being here, suppressed by all my childish fears
And if you have to leave, I wish that you would just leave
Your presence still lingers here and it won't leave me alone

These wounds won't seem to heal, this pain is just too real
There's just too much that time cannot erase

When you cried, I'd wipe away all of your tears
When you'd scream, I'd fight away all of your fears
And I held your hand through all of these years
But you still have all of me

You used to captivate me by your resonating light
Now, I'm bound by the life you left behind
Your face it haunts my once pleasant dreams
Your voice it chased away all the sanity in me

These wounds won't seem to heal, this pain is just too real
There's just too much that time cannot erase

When you cried, I'd wipe away all of your tears
When you'd scream, I'd fight away all of your fears
And I held your hand through all of these years
But you still have all of me

I've tried so hard to tell myself that you're gone
But though you're still with me, I've been alone all along

When you cried, I'd wipe away all of your tears
When you'd scream, I'd fight away all of your fears
And I held your hand through all of these years
But you still have all of me, me, me

Walking into her cabin, Shepard stops at her desk to pick up the photo of Kaidan and sighs. She moves to sit on the bed, face cupped in one hand as she stares at his image. How did we end up like this? Where did it go so wrong?

The door chimes and in comes the very man she's not ready to see, his eyes examining her weary countenance. She stands as he makes his way to her, setting the photo face-down on the bed before he takes her face in his hands and kisses her. Allowing herself a moment to memorize the touch of his lips on hers, she eventually pulls back, reaching up to remove his hands from her face. Kaidan frowns, "Shepard, about what happened back on the Citadel… I'm sorry for doubting you. After everything we sacrificed to save the Council before, I should have known you wouldn't try and kill one of them without cause."

Kaylin Shepard closes her eyes for a moment, visibly collecting herself before she speaks, her words soft and full of sorrow. "Kaidan… I can't do this anymore." His frown deepens, worry filling his eyes as she goes on. "I love you. Part of me will always love you, but I cannot be with someone who doesn't trust me."

Her fingers rise to silence his lips as he tries to respond, her voice slowly filling with strength. "No; let me finish. It used to be you would follow me anywhere without hesitation. If you weren't sure of what we were doing, you'd ask questions, but I never felt that you doubted me, just the course of action. Since I died and came back… you've lost faith in me, in my honesty, in my honor. First on Horizon, calling me a traitor for working with the Illusive Man. Then again on Mars, questioning if I had led Cerberus to the Archives. And just now, on the Citadel, when you kept a weapon trained on me even though I had lowered mine. Every time you prove your lack of trust in me I feel pieces of my heart being torn away and it's killing me. The fate of the universe bears down on my shoulders and, rather than helping me, it feels like you add more weight to my burden with your inability to believe in me. You used to make me stronger, Kaidan; now… you make me weak."

He stares at her, mouth opening and shutting several times before he finally finds what he wants to say. "Shepard… Kaylin… I love you. There is no one else in this universe for me; please don't do this. I'll work harder, not question you, back every idea you have if you'll let me stay. I'm sorry for hurting you; there is nothing I want to do less in this life than cause you pain." His hand reaches for her again, but she shakes her head as she neatly side-steps him to walk over to the fish tank, her back firmly turned to him.

"I've already spoken with Admiral Hackett; he could use humanity's second Spectre in a variety of capacities. There's a transport on the Citadel that will take you to the Crucible where you'll receive your orders."

Limned in the blue light from the fish tank, Shepard waits for him to speak, but his silence stretches on. As she turns, she sees the devastation on his face and nearly gives in, nearly begs him to forgive her and stay by her side. She bows her head and slowly slides a hand down over her face before looking back up, whispering, "Goodbye Kaidan. Take care of yourself and be safe."

With a shudder he pulls himself together, standing to attention and saluting her, voice becoming formal, "It has been an honor serving with you, ma'am. May I be dismissed?"

Heart breaking, she returns his salute. "Dismissed."

He strides past her, footfalls heavy as he heads for the door. As he prepares to leave her cabin, he pauses and says over his shoulder, voice ragged and pain-filled, "I'll always love you, Kaylin. Maybe when this is all over, you'll be able to forgive me."

The doors close at his back as Kaylin Shepard falls to her knees, body wracked with sobs as her world falls apart, wishing the universe didn't seem so damned lonely already without him.

Author's note: This is my first fic, so please be kind. While I love Kaidan to pieces, this possibility kept finding its way into my head and needed to come out. I hope others find it a decent bit of story; if so, I may write some more