What if Stiles was captured by hunters and subjected to mild torture before the pack got there to save him. They got him bandaged up at the vet before they took him home. Nothing was to serious just a few bruises and minor cuts but the next day the pack went to check on him he was gone and so was some of his stuff.

John (Stiles dad)
He may know where Stiles is but he stills blames himself for Stiles leaving.

Derek
He's gone, my mates gone, my other half is gone. That was all Derek could think about when he found out about it. He may have never told Stiles how he felt and what he meant to him but he had a feeling Stiles knew

I should have told him how I felt
I should have asked him out when I had the chance maybe he would have stayed
MY MATE IS GONE IM NOTHING

That is what Derek thought about everyday and he was a wreck

Scott
My best friend is gone and its my fault. I should have paid more attention to him instead of ignoring him for Allison. Scott blamed himself for Stiles leaving he hated himself for neglecting his best friend.

Erica
I'm going to kill batman when he is found. If he was going to leave he could have said bye. That is what Erica said but on the inside she was blaming her self

I should have talked to Stiles more
I should have been nicer to Stiles and not threaten him as much
I miss Stiles what if he never come back I cant be catwoman without batman

Lydia
That no good… she didn't even get to finish her sentence because she broke down crying. He was the only one who knew from the start how smart she was but didn't tell anyone. He liked her for her and she wouldn't give him the time of day. They had just started to become friends and he disappears

Allison
Is crying just like Lydia and is blaming herself because she is a hunter. She thinks if she would have paid more attention she could have warned Stiles about the hunters

Boyd and Isaac
They blame themselves because they never took the chance to get to know Stiles.

Jackson
Even though he may have been the Kanima and a ass to Stiles. He missed Stiles.

The pack look for him everyday for 6 months but gave up and hired a private investigator. A week after Stiles left the pack defeat the Kanima and Jackson now a werewolf. He helped look also and for some reason he felt like Stiles was a brother to him. They also told the sheriff what they were because they thought he needed to know. Derek was a wreck the pack had to snap him out of it and Lydia was the one to do it.

"Derek you have to leave this room" Lydia says standing in the door while Derek laid on the bed like a empty shell

"you have to get up and help us fight this thing that is trying to destroy Beacon Hills" Lydia says and Derek just stares out the window.

"If you don't help us then Stiles want have anything to come home to when he decides to come back" Lydia continues and that catches Derek attention because he looks over to her

"How do you know he is coming back" he rasps out like he hasn't talked in a while which he hasn't.

"I get this feeling and Stiles dad said that Stiles said he will be back one day" Lydia tells Derek sadly but is smiling because she got Derek to talk

"So are you going to help us save Beacon Hills for Stiles" Lydia asks holding her hand out and he nods getting up

"Go take a bath you stink" she says scrunching her nose up

2 years later

They had all graduated and Peter was back he was sad to here the spunky teenager was missing but didn't show it. 2 months after Stiles dad was told about werewolves he asked for the bite along with Scotts mom. Derek and the pack where fighting anything that threaten Beacon Hills. They had also rebuilt the Hale house to its original form.

They still missed Stiles and to this day the Private Investigator hasn't found a trace of Stiles. It was the 2 year anniversary of the day Stiles left and they were all camping in the woods each telling a story about Stiles. They did it last year as well