Based off the song- Here comes goodbye by Rascal Flatts

Here comes goodbye, here comes the last time

He laid next to her, tears streaming down his cheeks as he watched her. Every breath was a battle, every whimper sounding more and more like a struggle.

Lexie let out a gasp trying desperately to find the words that were failing to come out.

"Mark," she whispered.

"Lexie please stay with me, baby." Mark pleaded

"I'm dying..." Lexie whispered.

"No, no you're not, you're going to be fine. Please Lexie, you have to be alright." He stammered, struggling to get closer to her.

Here comes the start of every sleepless night

"You'll be fine," she gasped. "Without me."

Mark wiped at his tears, ignoring his own pain. "No, I won't. I love you Lexie. We're meant to be. We're supposed to grow old together and make beautiful children."

The first of every tear I'm gonna cry

Here comes the pain, here comes me wishing things had never changed

He regretted all those times he let her go. All those times he watched her walk away and didn't chase after her. He was blind to her love, caught up in everything else he didn't always know what he had.

And she was right here in my arms tonight, but here comes goodbye

He reached out, stroking her blood damped hair, watching as she drifted in and out of consciousness.

I can hear her say I love you like it was yesterday

And I can see it written on her face that she had never felt this way

All those times he was too stubborn to see it, all those I love you's he took for granted. Oh, how he wished he could go back and undo it all. Do it right from the beginning.

One day I thought I'd see her with her daddy by her side

And violins would play here comes the bride

He would see her walking down the aisle on Thatcher's arm as music would play. Their family surrounding them as they became husband and wife.

The cheers and applauds surrounding them as they would kiss. A kiss that would match no other.

Here comes goodbye, here comes the last time

She gasped again, bringing him out of his thoughts. Her breathing was getting more shallow and she fought to stay awake, so many things still left unsaid.

"I-I can't do this without you baby, I don't want to," Mark whispered. "I've always loved you, even when I was too stubborn to realize it."

I've loved you too," she let out a cough feeling more of the metal press against her. She whimpered, clearly in pain.

"Baby, I wish I could take this pain from you, I would do anything." Mark whispered.

Here comes the start of every sleepless night

The first of every tear I'm gonna cry

He tried crawling more under, he wanted to be as close to her as humanly possible. He knew she wasn't going to make it.

"Please tell Meredith I love her, please let her know I tried to be the best sister I could." Lexie said tearfully.

"No," Mark snapped. "You're going to tell her when you get out of here."

"Mark, I'm not..." she coughed. "It's not going to happen. Lexie sighed. She whimpered again, feeling more pain.

Here comes the pain, here comes me wishing things had never changed

And she was right here in my arms tonight, but here comes goodbye

"I'll be right back Lexie, just hold on." Mark whispered. He crawled back over to where he was remembering there was a hospital bag. He rummaged through it, sighing in relief when he found the morphine. He filled a syringe and crawled back over to where Lexie was barely hanging on.

"Okay, I got something for the pain." He inserted the needle into her, almost instant relief was brought to her, as her head started spinning.

"Mark..."

"Shh, don't try and talk, Lex. Just know that I love you, more than anything. It's okay to go, I don't want you to but I can't bare to see you suffer any longer, Lexie.

Why does it have to go from good to gone?

Before the lights turn on, yeah and you're left alone

"I love you," she whispered. Her eyes closing, her breathing becoming more shallow as she took her final breath. He laid there clinging to her. Knowing he just lost the love of his life.

All alone, but here comes goodbye

Oh, oh, oh, oh

Here comes goodbye, here comes the last time

Here comes the start of every sleepless night

The first of every tear I'm gonna cry

Here comes the pain, here comes me wishing things had never changed

And she was right here in my arms tonight, but here comes goodbye

Almost an hour later Meredith and Derek ran up to the scene finding both Mark and Lexie. Derek climbed in feeling for both of their pulses.

"They're gone," he whispered, picking up the empty vile of the pain killer.

"Both of them?" Meredith gasped realizing what had happened. Mark had joined Lexie by his own free will.