this is part one of a series of relationship headcanons. 1/?
besides his mother, the person whom derek most relates to is peter. with barely ten years between them, peter is a mix of big brother & parents to derek. when still younger, peter watched over talia’s kids quite often because the pack alpha is often busy & so while the kids adore their mother, they also grew attached to uncle peter. derek most of all. for a long time, derek introduced peter as his dad, but as he grew older, he stuck closer to the truth.
peter is the one derek relies on when he needs a friend, an open ear, support .. or just a shoulder to cry on. derek’s continuous struggle on full moons is an on-going project even through high-school, puberty hits & derek feels invincible most of the time, but clearly he’s not. peter’s there to protect him, to watch over him - despite the anger peter hides within. he puts derek first.
when derek tells him about paige, the cute human girl, peter is clearly alarmed, given derek’s known issues - befriending humans & living among them is one thing, but dating them when every full moon, or every temper tantrum could end lethal? bad idea. so peter works out a plan, it’s foolproof - or so they think. when she dies, though, derek’s world crumbles & the easiest way to deal is to blame. so he blames peter. he’s just a kid, he doesn’t know better at the time & cuts ties with peter, refusing to talk to him & it hurts them both. when derek is finally ready to leave the past behind, he’s already met kate - she’s kind & understanding, she keeps derek away from his uncle, filling derek’s head with lies to keep him from telling his family he’s in love with an argent. peter changes, it doesn’t go unnoticed, but derek never really finds out why.
after the fire, derek’s full of regret - naturally. he never had the chance to apologize to peter, to fix things. for the first few months after he settles in with his foster family, they don’t tell him where his uncle is being treated, but once he finds out, he spends a lot of time just sitting with him, hoping he wakes up. he tells him about school & basketball, about how his new family doesn’t understand him & that he still struggles with full moons. every single time he steps into that room, derek wishes for nothing more than to find peter back to normal, but he’s disappointed every single time.
after graduation, derek leaves town. he sees peter one more time before he leaves, he spends the whole night, he tells him about kate & the fire, he tells him about the guilt he carries each & every day, but peter doesn’t wake. it breaks his heart, but at least he knows his secret is safe with his uncle. he ends his last visit with an apology & leaves the triskelion medallion under peter’s pillow - it’s his way of saying goodbye, it’s his way of accepting that after years his uncle won’t wake up & that he’s found his peace with it.
when he finds out that peter is back, there’s joy, but at the same time he finds out that peter killed his sister laura, bit & chased scott, killed everybody else involved in the fire & is mad with the need for revenge. it’s safe to say his feelings are all over the place, but they come to an understanding for a while. derek never planned to kill peter, but he’s out of control & if anybody should have the hale alpha spark besides peter, it’s got to be him.
after that, it’s safe to say their relationship is .. difficult. derek has changed a lot since he was a boy & peter has, too. they had this intense bond that’s shattered, but neither of them are good at fixing it, or taking steps to do so. derek lets peter stay, but he also shuts himself off from him emotionally & peter’s stubborn, so that’s not helpful either. they have this .. dance for a long while, but peter’s ego stands between them more often than not, but at the end of the day .. when needed, even if for ulterior moves / selfish reasons, peter helps him, which is derek’s proof that the uncle he adored when he was a child is still in there.
post season 6, i need to believe that they find each other again & talk. derek has had little to say when it came to peter & beacon hills - he almost died that night & peter had worked with kate to kill scott, so .. he had to let them lock him up. but when peter escapes & derek finds out he helped save beacon hills, too, he’s determined to find him.
