Edge runs into his room telling Sans to keep away from him.
Sans watches the door slam but still flinches when it happens because of how loud it is. He stands rooted to the spot, frozen by the very sudden explosion of anger, and unsure how he should react to it. Or if it really was anger. But he can hear things break inside the room. And things keep breaking. He suddenly feels weird standing in the hallway. He retreats to the couch downstairs, unsure if he's retreating because he feels listening would be invasive, or because some part of him is afraid by the violent action. Sans' default response to threat is to dodge, avoid, and run away, and he wonders for a split second if he's letting his instincts force his reaction. But once he's sitting on the couch, leaning slightly against the arm rest with his hands as he stares at Edge's door, he can't seem to get himself to move.
He can hear the destruction still going on upstairs, and he starts to flinch a little more with each crash and bang. a small voice in the back of his head starts trying to grab his attention. "shouldn't you call somebody? He's been going for too long. He's not calming down. Maybe you should call someone. Papyrus? No. No he can't. Red? No. that would make things worse. then... who? Should he call Papyrus? or... or fuck... Toriel?? Someone?? He's not stopping...." But Sans squashes down the intrusive thoughts and worry. And he just sits, fingers digging into the arm rest.
Suddenly, like a whip crack, he can feel more than smell the scent of expelled magic explode from Edge's room. Sans turns rock-solid on the spot, his nervous shifting and picking at the couch's material freezing in place and he swallows his breath. And what follows is silence.
He lets go of the couch, noticing his hands are trembling only vaguely. He sits, breathing shallow to try and hear, but he can't hear anything more.
Magic tingling at his temples, he pushes himself off the couch and with shaking legs, stumbles up the stairs. He reaches Edge's door. He considers knocking but stops. Instead, feeling only slightly ashamed, he leans closer against the wood. He hears Edge's voice but he can't make out the words. He doesn't think he wants to. But He hears Edge talking, meaning that the explosion of magic wasn't enough to knock himself out. He leans away, quietly letting out a long breath. He steps away from the door weakly. There's no more sounds of violence, and he figures that blast of magic was probably the final blow of the tantrum.
He slowly walks back down the stairs despite his better judgement. The urgency to call somebody isn't as strong now and he manages to stamp it down until he can tell he's not going to follow through with the idea. The burst of anger and destruction has him rattled (heh) and not knowing what kind of state Edge must be in... let alone his room... has him extremely unnerved. But he feels Edge needs space. He said so, after all. Sans only feels slightly conflicted in wondering if he's really doing it for Edge's good or his own reluctance to put himself into a of line of fire, even an accidental one. He sits back on the couch, a little more emphatically, and stares at the off TV in front of him. After a few minutes he turns it on. He pretends to watch it but his thoughts are spiraling around, trying to piece together everything that just happened.
It must have worked in some way because he loses track of time.
A while later, he realises it's been a little too long, and he hasn't heard a single noise from Edge's room. He stands in front of the door, trying to listen but it's silent inside. He pulls his nerves together and knocks. There's no reply, so he knocks a little louder, this time calling Edge's name in a nervous question. Still no reply.
Sans swallows, his mouth suddenly feeling dry. He leans away from the door, looking it over as if it would give him some kind of answer as to what to do. He considers knocking again, louder, but he doesn't think banging on it with a fist will do much to help things. But Edge isn't answering, and he couldn't hear a single noise from inside. A dark thought rolls through him, and before he can focus on it or his actions too much, Sans teleports inside.
He's at first struck by the utter destruction inside. The chaos and broken furniture worse than what he hadn't even been trying to imagine. The sensory overload has him briefly looking around in stunned silence. He notices Edge lying curled in the corner and for a brief, mad second, ice runs through him. He doesn't even know why. Maybe being around humans for so long has warped his idea of how things work. But the split second is enough to make him lean closer, quiet but urgently, close enough to see the other skeleton clearly. To asses him.
He's asleep, curled in on himself in a way Sans can't recall ever seeing before. Not that he's had too many chances of seeing Edge sleep, but enough to know... this isn't normal. Something inside him cracks just a little. He can't figure out if it's because when asleep and with less of a scowl on his face, Edge looks just a little TOO much like Papyrus, or if it's purely due to the sudden very real and very tangible evidence of how Edge is coping with this. Or rather.... not coping. Sans doesn't analyse it too closely. But he does focus on the fact that a person in his home, one he may not always like but who he couldn't pretend he'd be happy to see gone, is hurting.
The sudden sympathy is too much and he can't just leave him like this. Looking like that. Alone in his room surrounded by debris. Sans' feelings have numbed a little, the sharpness from the anxiety and tension gone, but not replaced by relief. He teleports from the room, wandering to the linen closet and almost on auto pilot pulling out the nearest blanket, before he warps back.
He doesn't hesitate to stare any longer. He simply moves closer, taking care not to step on any glass or dislodge any broken wood that may make a noise, and throws the blanket over Edge, making sure it doesn't hitch up and that Edge is covered. He steps back, forcing himself not to stick around ogling him any longer (although some weird part of him wants to. perhaps to make sure he's ok. he can't tell). But he forces himself to teleport out the room and back downstairs.
He plops down on the couch. He puts both arms over his sockets, closing them and leaning far back against the backrest with a drawn out groan.
He stays seated like that for a very long time.