Okay this is a slight AU. Derek and Addison got back together 3 months ago. Derek and Meredith are friends. Mark is back in New York. Mark has a 16 year old daughter, Madeline Grace Sloane, from a drunken fling years ago.
"I can't believe I'm stuck in the pit all day and you get to scrub in with McWife," Christina grumbled to Meredith.
"Trust me I would swap if I could. I still feel so awkward around Addison," said Meredith brushing past a stunning brunette.
"Excuse me are you talking about Addison Shepherd?" she asked Meredith.
"Uh yeah, she is neo-natal if you're looking for her," said Meredith, looking at the girl who on closer inspection was a lot younger than she first appeared. There was something familiar about her, but she couldn't put her finger on what it was.
"Uh it was actually Dr. Derek Shepherd I was looking for. Do you know where I could find him?" she asked.
"Um… he's in surgery right now," said Meredith looking towards the board.
"What do you want with him?" asked Christina eyeing her suspiciously.
"That is of a personal nature," the girl stated.
"What are you another wife?" Christina muttered under her breath.
"No," snapped the girl, "hadn't you two interns better run along"
"What a little…." Said Christina, "barely out of diapers"
"Sorry that was rude of me," said the girl, "Could you point me to the gallery abover where Dr. Shepherd is operating?"
"Um…." said Meredith unsure about telling an unauthorized civilian.
"He's expecting me," she said.
"It is OR4 3rd door on the left," said Meredith uncertainly, "it could be a while until he is done though"
"That is okay. Thank you," said the girl.
Half an hour later, Derek had just finished his surgery. He washed up and walked out onto the corridor. The first people he saw were Addison and Meredith, they were discussing a paitent.
"Oh hi honey," said Addison when she saw him, she went over and kissed him lightly on the lips.
"Well I didn't expect you to forgive an adulterous bitch Uncle Derek," he heard that voice and knew it immediately.
"Gracie," said Derek turning to face none other than Madeline Grace Sloan, his goddaughter. He always called her by her middle name, she hated the name Madeline.
"Yeah, hi," she said coming over and hugging him, "You miss me?"
"Of course I missed you. You've changed so much, look at your hair," the last time he had saw her she was a blonde.
"Yeah I got bored with the blonde. And you better have missed me, since you just upped and left without so much as a goodbye or a forwarding address," said Grace her tone suddenly changing.
"I sent you a letter," said Derek looking down at the ground looking ashamed.
"2 weeks later," she said.
"I'm sorry," he said.
"It's fine, perfectly understandable given the circumstances," she said shooting a dirty look at Addison.
"Uh… Dr. Grey could you go and check on Mrs. Steinberg," said Addison.
"Dr. Meredith Grey?" said Grace.
"Yes," said Meredith.
"Yeah we met earlier, I should have introduced myself then, I'm Grace Sloan," she said
"I believe you have met my father. He told me about you," she said shooting a glance at Derek.
"Dr. Grey, Mrs. Steinberg?" said Addison.
"Oh right sorry. It was nice meeting you," said Meredith.
"Nice to meet you too," said Grace.
"What are you doing here?" said Derek.
"What I can't visit?"
"Of course you can, you should have called we would have picked you up at the airport," said Addison.
"I can't believe you took her back," Grace said to Derek.
"Gracie," said Derek warningly, "Be nice"
"I know everything that happened before I left was rough on you but…"
"Wasn't just before you left…."
"So where are you staying?" Addison interrupted.
"Hotel," said Grace.
"With your dad?" asked Derek.
"No calm down he's in New York… I think he has a major surgery anyway,"
"So you just came on your own?" said Derek suspiciously.
"Yes, I wouldn't have bothered if all I was going to get was the third degree," she said rolling her eyes.
"Alright, I didn't mean it like that. I mean everything is okay isn't it?" he asked worriedly.
"Uh yeah fine," she said shooting a glance at Adddison.
"Well I'm finished now, why don't I take you to lunch," said Derek, "Addie when do you finish"
"6 hours," she said looking uncomfortable.
"Okay looks like it will just be the two of us then. Go downstairs and I'll meet you there in about 10 minutes," said Derek.
"Okay," nodded Grace.
Once Derek had gone, Grace turned to Addison.
"Gracie, please he doesn't know," said Addison for once sounding rattling.
"I guessed that, he wouldn't have took you back if he knew you stayed with Dad," said Grace her eyes burning with anger.
"You can't tell him"
"Give me one good reason why I shouldn't!"
"Because we are happy, we're getting back that. Don't you want Derek to be happy?"
"Of course I do. I just think he can do better than you."
"We love each other, staying with Mark was just a mistake," said Addison nearly begging.
"Would you still be with him if you hadn't caught him with someone else?"
"No. I knew it was a mistake, I belong with Derek. Please Gracie, you don't want to hurt him like that I know you don't."
"Fine I'll keep your dirty little secret because I'm not going to be the one to break him this time, but one screw up and I will tell him," said Grace before storming away from Addison.