Peter stared at the wedding picture of Derek and his husband.

Stranger was Stiles. Derek was the one he was cheating on. With Peter.

"I should have come to your wedding," Peter said tonelessly. Because then he would have known Stiles. Then Stiles would never have approached him like that at the club. Then Peter would have never had sex with Stiles.

"Don't start with that again." Derek picked up the picture to have a closer look at it, his voice distant as if he was caught in memories for a moment. For which Peter was grateful because he needed a second to compose himself.

"Let's start fresh." Derek put the picture back.

Peter could only nod numbly, his mind racing. With any other person, he would just wait until Stiles got home and watch the drama unfold. He would be looking forward to a front-row seat to the shitstorm coming his way but this was Derek. The one person he cared about. He was here because he wanted to be a part of his life again.

Peter's first instinct was to leave. Make up an excuse and leave before Stiles arrived. Retreat and regroup until he'd figured out how to deal with the situation. However, if he left now, what would Derek think of it? Would he even agree to see him ever again? Peter was on parole, he knew that. He'd hurt Derek by blaming him for what Kate had done and when Derek had reached out to him with the invitation to his wedding Peter hadn't even bothered with responding. Today might be his last chance.

On the other hand, if he stayed he could easily ruin Derek's marriage. Not that it was his fault, there was a reason Stiles was listed as Stranger on his phone. He'd never met Derek's husband and at the club, it had been Stiles who had approached him. He hadn't been wearing his ring either.

Peter didn't have a way of knowing what he'd been getting into.

But Stiles had known. Not who Peter was but it was clear that he was not Stiles' first hook-up. As far as he could tell, this had been going on for a while and Peter was just the latest guy in a long line of hook-ups. At least they had used condoms.

Oblivious to his inner crisis, Derek said something about the food they were having and excused himself to check on something in the kitchen.

The second he was alone, Peter got his phone out and wrote a message to Stranger aka Stiles.

Hi, my name is Peter Hale. I'm currently at my nephew Derek's place, waiting to meet his lovely husband

Peter hit send and just hoped that Stiles would read it before he arrived.

WTF? Came the answer a few seconds later.

I suggest we pretend that we don't know each other, Peter wrote. It was a shitty solution and not fair to Derek but it was the only thing he could think of. He just had the time to send the message out before Derek came back and couldn't wait for Stiles' response. He did, however, made a mental note to chew Stiles out in private later. Cheating on somebody like this was one thing but given Derek's background with Kate … Peter was ready to murder Stiles. He would play nice, though. For Derek's sake.

"Didn't know you cook," Peter said with a forced smile.

"I used to cook for Laura and myself," Derek answered. "After … you know, I needed something to get my hands busy. Turned out I like it. Stiles would live off take-out and pre-made meals if I let him."

Derek hurried to gloss over Laura but Peter caught his expression when he mentioned his sister. After the fire, they'd only had each other since Peter had ghosted them. And then Laura had died as well.

"Need help with anything?" Peter asked in an attempt to lighten the mood.

That's how he ended up in the kitchen with Derek. Peter enjoyed good food but he'd never bothered with learning how to make it. So Derek put him on light duty with putting together the salad.

Peter was dreading the moment Stiles would stand in the door but it was surprisingly easy to not think about that too much and to just enjoy Derek's company. After a few minutes, they had a light chatter going on and Peter would truly enjoy this if it weren't for the impending doom.

Without intending to they had walked down the memory line and were now fondly talking about the disaster that had been Christmas of '98.

"Talia refused to even look at me for two months afterward," Peter remembered. "But her face … priceless."

"She was so mad at you." Derek shook his head with a fond smile on his lips. "But she kept that ugly thing in a dresser in her bedroom."

"I didn't know that." Peter looked up from the cucumber he was cutting up. "Thought she threw it out the next day."

"No, she still had it when …" Derek didn't finish the sentence but he was interrupted by the front door opening anyway. "That's Stiles."

Derek hurried to dry his hands and then Peter followed him to the living room to officially meet Stiles.

"Hi, I'm Stiles," Stiles introduced himself with that familiar broad grin. "You must be Peter, nice to meet you." He delivered the line a tad too cheerfully but that could get chalked up as nervousness over meeting the only family his husband had left.

Before the situation got awkward, Stiles was quick to excuse being late with a meeting he had to attend and while they moved this back over to the kitchen, he ranted about another professor who'd been holding up the whole thing with winded explanations and unnecessary questions.

"But that gave you two time to catch up," Stiles finished his rant. "You haven't seen each other in how long?"

"Years," Peter hurried to say before Derek could name the events marking those dates. They had talked enough about their dead family. Not that Peter knew what else to talk about, Derek was basically a stranger to him. Same for Stiles aside from the fact that Peter knew what sounds he made when he came and what he could do with his tongue. Which were not appropriate topics for a family dinner.

When they sat down, Peter ended up across from Stiles. Peter glared daggers at him but was only met with that grin that had turned unnerving a while ago.

Peter played nice. He complimented the food and asked polite questions about life as professors at a university. Stiles was teaching math which kind of complemented Derek's astrophysics.

The other day Derek had told him how he'd met Stiles in college and how they had circled each other for quite a while before Stiles had finally said fuck it and had just kissed him. The second part was Stiles' addition to the story, Derek had left it out in his version. It was interesting to hear Stiles' version of the events but what Peter struck the most was how affectionately Stiles was talking about Derek. If Peter didn't know better he would have sworn that Stiles was still madly in love with his husband.

At the same time, Stiles used every chance he got to ask how Peter liked New York so far, if he'd met interesting people, if he had somebody waiting at home for him? Stiles backed out of that question quickly when Derek told him in a low voice that Peter had lost his wife in the fire.

"No, it's a valid question," Peter said. "I loved Olivia very much and I still miss her but it's been a long time. I'm open to meeting new people but I rarely meet somebody worth seeing again." He looked Stiles straight in the eye with that. Two could play this game.

Stiles raised his glass in a touche-manner.

"I have to show you this one club, then," Stiles said. "A good place to meet new people."

Derek did throw him a questioning look at that but Stiles shook his head which Peter interpreted as later.

After dinner, they cleared the table and sat down with another glass of wine. Their conversation turned to more neutral topics, students were a never-ending source of hilarious stories and Peter had a story or two to tell from his travels, and he had to admit that he was having a good time.

However, when Derek excused himself to the bathroom for a moment, Peter leaned forward and hissed at Stiles: "What the hell were you thinking?"

"I didn't know that you're his uncle," Stiles hissed back.

"That's not the point. You're cheating on my nephew."

"Does that mean next Saturday is canceled as well?" Stiles blinked innocently at him.

Peter was about to leap over the table to strangle him but Stiles shook off the silly expression and sobered up.

"Believe me, this is not what I intended," Stiles said and for the first time, he did seem remorseful.

"Get your shit together or divorce him." Peter glared at him. "Stop playing games with him."

Other men had crumbled when Peter had looked at them that way but Stiles wasn't intimidated in the slightest. Quite the opposite, his gaze turned dark as well.

"I thought I made myself clear," he said coldly. "My private life is none of your business."

"Not any longer." Peter shook his head. "Not when you're stringing along my nephew."

"You haven't been in the picture for years," Stiles reminded him. "Where have you been when he needed you? And now you care? Please." Stiles snorted.

He was right. Peter couldn't deny that.

"I'm here now." He wanted to say more but Derek was coming back so Peter left it at glaring daggers at Stiles for a moment longer.

Peter left Derek's place with mixed feelings. He had enjoyed Derek's company and it had turned out that they still clicked. Derek had to check his schedule but they had agreed to see each other again soon. At that Stiles had chimed in with the idea again of hitting that club on Saturday which had gotten him a confused look from Derek and another death glare from Peter. Stiles had been impressed by neither.

Peter had no idea how to deal with the situation. The right thing to do would be to tell Derek but he doubted that he would take it lightly. It most likely would destroy their marriage, which probably was broken beyond repair anyway Derek just didn't know it yet, but it would put Peter in a bad light as well. Not that he cared about things like that but he did care about Derek's opinion of him.

Peter decided to sleep over it but things did not look better in the morning.

Neither Derek nor Stiles contacted him and he didn't reach out to them either. He didn't know which one he wanted to talk to but he wanted to have that conversation in person.

In Stiles' case, he was tempted to just murder him in a back alley, maybe behind the Jungle to give it some meaning. If Peter was right, Stiles had been picking up guys there for quite a while, the police shouldn't have a problem with finding suspects who were not Peter. Problem solved.

However, as his husband Derek would be the main suspect and Peter did not want him to go through that again. So no murdering Stiles.

In the afternoon Peter was still not sure how to handle the situation but he got a message from Derek.

Sorry, Stiles is an ass. Can we talk over lunch on Thursday?

Peter read the message over and over again but it stayed as cryptic as before.

Wanted to talk to you anyway, he finally wrote back and asked about the when and where. Looked as if he would talk to Derek first. They hashed out the details and then Peter had time until Thursday to figure out what to tell Derek.

A few minutes later his phone chimed with a new message, this one from Stiles.

I know you hate me right now

Understatement, Peter wrote back.

Just don't do something drastic like leaving, talk to Derek first, he missed you.