Derek gets tortured, sexually assaulted and abandoned by the only people who may give a damn about him on occasion.

Stiles is a huge asshole to everyone, including Lydia. Peter is stepping up the creepy.

Scott: "Call it again."
Stiles: "It's not here. Okay, so you lost your phone. Why don't you just get a new one?"
Scott: "I can't afford a new one. And I can't do this alone. We have to find Derek."
Stiles: "Well, A, you're not alone. You have me. And B, didn't you say Derek walked into gunfire? He sounds pretty dead."
Scott: "Argent's plan was to use him to get to the Alpha– they're not gonna kill him."
Stiles: "All right, so then just let them do what they're planning, you know? They use Derek to get Peter– problem solved."
Scott: "Not if Peter's going after Allison to find Derek! I can't protect her on my own. Which means we either find Derek first– just– just help me!"
Stiles: "You know, you probably lost it when you two were fighting. You remember that, when he was trying to kill you, after you interrupted him trying to kill Jackson? Are you starting to see a pattern of violent behavior here?"
Scott: "He wasn't going to kill anyone. And I'm not letting him die."
Stiles: "Could you at least think about letting him die? For me?"

Stiles is protective of Scott. He is leaving Derek in the Argents' clutches to let Peter and them take each other out. He thinks this is the perfect way to get rid of all their problems. Stiles is pragmatic and willing to let Derek die for his perceived crimes. Asking Scott to think about letting Derek die, just for him, Stiles sounds like a whiny brat. No. I don´t want to think about him anymore. I just want him out of my life. No. I don´t want him to come back and haunt me. Please let this be over.

Kate calls Derek´s expression sour. Oh my God. Did she usually call him that? No wonder Derek was pissed when Stiles called him sourwolf.

Derek never told anyone that Kate, his lover, was the one who burnt his family alive. So how does Stiles know about this later?

Stiles calls Lydia cold. How does Derek know about this later?

Stiles: "Lydia! Run! - Don't kill her. Please."
Peter: "Of course not. Just tell me how to find Derek."
Stiles: "W–what?"
Peter: "Tell me how to find Derek Hale."
Stiles: "I don't know that. How would I know that?"
Peter: "Because you're the clever one, aren't you? And because deception has a particularly acrid scent, Stiles. Tell me the truth– Or I will rip her apart."
Stiles: "Look– Look, I don't know, okay? I sw–I swear to god, I have no idea."
Peter: "Tell me!"
Stiles: "Okay, okay, okay, look, I– I think he knew–"
Peter: "Knew what?"
Stiles: "Derek, I think he– I think he knew he was gonna be caught."
Peter: "By the Argents?"
Stiles: "Yeah."
Peter: "And?"
Stiles: "When they were shot, he and Scott– I think he took Scott's Phone."
Peter: "Why?"
Stiles: "They all have GPS now. So if he still has it and if it's still on– you can find him."

Stiles knew that Derek was captured by the Argents and he knew how to find him the whole time, ever since that conversation in Scott's room. He left him there knowing the Argents might torture or kill him and he kept it to himself to protect Scott. Or maybe because he wants Derek Hale to be somebody else's problem and he could finally get over his conflicted feelings of fascination and annoyance. It's cruel, more cruel than he knows.

Derek took the phone hoping that Scott and Stiles would come for him, that someone would come for him. Considering how Scott ends up finding him later, the phone trick was probably aimed at Stiles. And Stiles leaves him there to die because Stiles doesn't trust Derek, not even enough for the benefit of the doubt. He thinks Derek chose Peter and that's that. Game over.

Stiles wears blue checkered shirt above a black shirt with the imprint of the peace symbol. At school he wears a blue-teal checkered shirt above a plain teal shirt.
At the ball he wears a black suit, a white shirt and a grey tie.

Derek is bare-chested the whole time.

No hate, just cruel insensibility in reference to Stiles, and hopeful desperation in reference to Derek.