Derek remembered the first time Stiles told him he was in love. Derek felt his stomach drop and his heart clench. The words "I met someone and I think I'm love" jumped out at him and killed any hope of Stiles being at the terminal when he got back.
Derek remembers the wedding invitation. It arrived one day before a mission and Derek cried. He cried like he never cried before. His howls were heard throughout the building and howls from surrounding wolves reached his ears. He wasn't the only with a broken heart that night.
Jackson pounded and banged against the door begging to be let in. When he finally got the custodian to open the door Derek was sobbing and had a gun held up against his temple. It took Jackson, Danny, Isaac, Scott and Boy hours to convince Derek to put the gun down.
Derek would've made up an excuse. A reason as to why he couldn't make the wedding. But his tour was over. And he was already on a plane back to Beacon Hills. His tux was already waiting for him in his apartment, chosen by Lydia of course.
He showed up with Lydia on his arm. They looked like the perfect couple. But they weren't. Lydia was obviously the Alpha Female to his Alpha Male but she wasn't Stiles. She wasn't pack mom. She just wasn't anything Derek could want. But she was what he had. And them being together was just expected.
Derek remembers the bliss in Stiles eyes when he finally said "I do" to Ryan. Who marries a guy named Ryan anyways. Its such an "ugh" name. Lydia says he's jealous, and she's right. The pack looks at him with sadness. None of them offer a congratulations to the happy couple. They leave as soon as the ceremony is over and again as soon as the formal part of the reception is over.
Derek remembers the look of hurt, betrayal, anger and disappointment in Stiles eyes when he watches them stand and leave. Ryan barely spares them a glance.
Derek has it saved on his phone. The text where Stiles tells him that Ryan cheated on him with a stripper named Emerald. He told Derek "I hope you're happy". But Derek wasn't happy. He hasn't been since he got that letter.
Derek hasn't seen Stiles for 5 years. And in those 5 years he and Lydia had twins. The Alpha pair has to make pups after all. Its in their job description. Erica and Boyd have a little girl named Claudia. Jackson and Danny have 3 surrogate mothers. One of them is going to have Dereks DNA. Scott and Isaac have 2 surrogate mothers. The Hale pack is loaded obviously.
Stiles sees Derek one day. With two twin boys with his eyes and Lydia's complexion. Stiles isn't stupid by any means. He knows Lydia and Derek are Wolf married. And by the look on Derek's face he's perfectly happy where he is. And Stiles isn't happy because maybe that should be him waiting for Derek on a bench. Not her.
He stays single. Stiles that is. Not bothering with dates or anybody. And that's his mistake. Because some people take rejection wrong and some people end up dead in a ditch.
Colonel Hale receives the news that Stiles is dead when he is getting back from a meeting. Lydia is crying and clutching at her swelling stomach and her phone is on the floor the words "Stiles is dead" jump at Derek and he crashes to the floor. Tears and howls of rage fill the area. And once again wolves answer his cries.
The funeral is simple. Stiles wouldn't have wanted anything extravagant. The Hale Pack is there. More powerful then ever. They leave before the Father is done with his sermon. Stiles was Roman Catholic who knew.
Derek remembers when they meet again. Stiles is at his bedside and Derek is old and wrinklely. The first thing Stiles says is "EW, damn sourwolf you really let yourself go" and Derek knows he'd be okay with not waking up the next day.
And he doesn't. But he does. In the area where he and Stiles first met. And Stiles is there holding out his hand saying "Remember this?"