I'M POSTING THIS CHAPTER AT THE SAME TIME AS THE CHAPTER 7. If you haven't read chapter 7 yet, you should probably do that first. Just a warning.

A/N: We'll get back to Sherlock and John next chapter - sorry. I honestly wouldn't feel right posting this chapter as its own update, which is why it's being posted at the same time as 7, because John isn't in it. It's a different kind of chapter. But I like it, and I really want it to be included, so here it is. It's just Mary background and you get to see Mary and Lestrade's relationship.

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"How do you do it?" Lestrade asked Mary as they sat down in Mary's living room. He'd called her as he left Sherlock and John in his flat and she'd invited him over. He needed someone to talk to, and who better? There was something about her that helped him open up - she was a bit like John in that way. "How do you handle it, knowing John's - with other people?"

Mary smiled gently. "I know he needs you, in addition to me. What kind of wife would I be if I denied him what he needs?"

"A normal one?"

Mary shook her finger at him. "Most men - and women - don't need extramarital relationships like the one John has with you. They want them, sure, but John wouldn't last without you. He literally needs your friendship, and I understand that sometimes that friendship is more."

"But how does that part not bother you?"

"I knew what your relationship was like before John and I were serious. If it had bothered me, I would have left him then. I very much believe that the people in someone's life affect who they are. I've never known him without you, and what if he'd be very different then? I love him the way he is, and he is the way he is because of his current relationships. Getting rid of you or changing your relationship could change him in a way I'd rather not risk. He never said it, but I knew there was a possibility that that side of the relationship would return, at some point. I don't have to tell you how much you've helped him - his history with you, the support you offer each other. It's beautiful. You're his best friend."

"Have you always felt like this?" Lestrade asked and quickly added: "I know it's none of my business. I'm just curious how someone learns to be so..."

Mary shrugged. "I'm an open book, Greg. I have no secrets anymore. I used to be the exact opposite, actually, about relationships. I expected men to drop everything for me. I expected them to make me happy, and when they didn't, I used alcohol to make me happy. You know how that worked out. At AA, I learned that no one is responsible for my happiness except me. I learned to look at what I needed from a relationship, what I needed John, or any man, to do rather than what I didn't want him to do. He has to respect me. He has to be kind. He has to be dedicated to our relationship. And I realized that being dedicated to you doesn't mean he can't be dedicated to me. He's quite devoted to both of us, and he's able to do that. It's unreasonable to expect him to spend all his time with me - we both have jobs, we both have our own friends, we have different interests. How does it affect me what he does on his own time? As long as he isn't losing all our money or getting hurt or coming back to me angry, he deserves his freedom and I trust him to make good decisions."

Lestrade nodded slowly. "You said... people are affected by relationships they're in. I don't mean to overstep boundaries, but as a friend, are you worried about Sherlock being back?"

Mary sighed. "Yes. The John I love is post-Sherlock Holmes. I don't want him to be unhappy, but honestly his grief has helped us connect on significant levels, and I have no doubt that he will be a changed man now. Even if his grief stays, which is possible."

"Have you talked to him about it yet?"

"A bit. I've tried to be very clear on the matter. He should do what makes him happy. If he finds that being with Sherlock again is what he wants, if he no longer wants to be with me...well."

Lestrade winced. "You wouldn't...I don't know, fight for him?"

Mary widened her eyes. "No. He's an adult and he can make his own decisions. I would be heartbroken, of course I would be, but if he's going to be happier one way, I won't pressure him to be a different way. And it's possible I wouldn't mind sharing him with Sherlock. If that's what he wants, and if I can still get what I need from our relationship, who knows?"

Lestrade thought that over for a few moments. Mary sipped her tea.

"I'm not telling you this to invade his privacy, of course," added Mary, breaking the silence. "He has a right to that, but I want you to know where I stand, for reference. I consider you a friend and I don't want you to feel conflicted if you find out something is happening between them. I also don't want you to alter your relationship with him for me. I know you and John have talked about that a bit and I mentioned it earlier, but I want to be explicit on the matter: As long as he's happy, I'm happy."

Lestrade nodded. "You're an amazing woman. I'm glad John has you, he's truly earned that kind of...unconditional love. And selfishly, I'm glad you feel the way you do because I need him too."

Mary reached over and touched his hand. "How are you doing, Greg? Sherlock's return has to have affected you."

"It has. It's more weird than anything, honestly. I'm thrilled to have him back, I am. It's like a weight's been lifted, you know?"

"You don't sound thrilled."

Lestrade moved his head, granting her that observation. "I guess I'm worried."

"About?"

Lestrade shrugged and gave a small smile. "I'm afraid I'm not as much an open book as you are."

"I can keep confidences, Greg. I know better than most that talking about something can help. I promise not to tell John anything you say."

Lestrade took a deep breath, ran a hand through his hair. "I guess... I wish I were more like you."

"What do you mean?"

A faint blush tinted his cheeks and he avoided her eyes. "Between us, Mary. If John's relationship with Sherlock develops the way I think it will...I don't know what I'll do."

Mary's eyes widened. "You're in love with him too? With Sherlock?"

"Yeah. And three years ago, I would have been fine with their relationship developing any way they wanted. I've accepted that nothing can happen between Sherlock and me, I've known that all along. And in walked this John Watson fellow and Sher was clearly smitten even though he wouldn't admit it and I was happy for him. But I've been a Sherlock-replacement for John for the past three years. Sherlock was the original best friend, the original exception to his heterosexuality, and now that he's back - I don't know where my place with either of them will be."

"You don't think your relationship with John is that fragile?"

"No, I think his relationship with Sherlock will be that powerful."

Mary looked for a moment like she wanted to cry. "What was your relationship like when he and Sherlock lived together?"

Lestrade shrugged. "Strictly professional. Nothing more or less. And I don't want it to go back to that, I don't think I could handle it. But I know that's what Sherlock will want, and John could easily fall into that with him."

"John loves you, you know he does."

"I don't doubt that, Mary," said Lestrade with a smile.

"You'll talk to him about it, then? I mean, give him some time to adjust to the changes, but then explain what you want. I'm afraid that's the only advice I have - John's a good man, and he wouldn't hurt you on purpose."

Lestrade nodded sadly and they finished their tea.

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A/N: Spoiler warning: This isn't a Johnlock fic. I don't want people to get their hopes up (or down, whatever) for something that won't happen here. Relationships involved are as follows: Friends-with-benefits John/Lestrade; married John/Mary; queerplatonic-ish John/Sherlock, with a touch of romance but no sex; and strictly platonic Sherlock/Lestrade. That doesn't necessarily account for all the feelings between the characters, but it's how the relationships will work.