Dean had been on his way in from the Quidditch pitch, where he'd mostly been watching a few others fly, when he decided to forget heading in at all for a bit. He'd spent most of the summers hols outside. He was glad to be back at school, really. For the most part, anyway. But with school starting up, they'd be spending most of their days inside the castle. And time went back quick when classes were going on - it'd be winter soon enough. He had some reading to do, but it could wait. Dean decided to just amble about outside for a bit. It was a nice enough sort of day that being out in the sun sounded like more fun that plopping across his bunk with schoolwork.
He headed for the lake, wandering a crooked sort of path. He should have brought his sketchbook with him, but he didn't feel like wandering back up to the Tower to fetch it.
Dean froze in the middle of pondering whether or not he wanted to get over being lazy and go get it when a scream cut through the air. Definitely feminine, and it sounded like whoever it was, someone was half murdering them.
Dean had always suffered from a bit of a white knight syndrome, when it came to girls. Or people he cared about. He wanted to protect them, and rescue if they needed it. He was usually drawn to the sort of girls who didn't NEED that kind of treatment, though. Which made it more of a hindrance than a help. But it was part of who he was, and he ran off toward the sound of the screaming without thinking twice.
Dean was a wizard, and he wasn't a bad one. But he still thought like a muggle first, which meant that when he caught sight of Daphne in a squid leglock, being dragged toward the water, his first reaction wasn't to grab for his wand, but to grab her "What the hell - let her go!" The squid was, usually, a friendly sort. Dean wasn't even sure it was trying to hurt her now. But she definitely didn't look like going for a swim was in her plan.
He managed to run up in time to catch her wrist before she hit the water, trying to catch her and draw her back. Unfortunately, in a battle of strength between Deans and Giant Squids, the squid came up the winner. The squid just pulled, and Daphne was yanked into the water, though not beneath it, and Dean lost his grip on her hand.
Which was when he remembered his wand. "Let go!" he yelled, as if the tentacles might listen. He shot a weak stun toward a waving tentacle that wasn't holding on to Daphne, not wanting to hurt the thing. McGonagall would probably have his head if he did.
The stun seemed to work a bit, since the tentacles loosened. Dean waded waist-deep into the water to wrap an arm around Daphne, trying to get enough of a grip to drag her back toward the shore of the lake before the squid decided that it wasn't ready to let go after all. "You all right?" he asked, slapping with his free hand at the tentacle that had wound around her ankle to get it to loosen.