Ruffnut was having a bad day.
She had been woken up with a bucket of cold water thrown over her by her annoying twin. (And yes it had happened before, but it wasn't a easy thing to get used to,) Then her hair has been knotted badly after she lost her hairbrush and she had been forced to leave her hair looking like a birds-nest, though she had somehow messily forced into her usual hair-style.
She had then been late for dragon training, leading to a dull lecture from hiccup and snickers from Snoutlout and her brother. God, she wanted to punch them. She had then been bitten by Barf after she had startled him and then been put to a fight against Astrid, since Hiccup said they can't always rely on dragon if they were invaded.
After Astrid had beaten her with a hard whack to the head, her pride had taken another blow after she heard Snoutlout say cruelly to Fishlegs "ha, she's so weak. Not much in the looks or personality department either!" And Fishlegs, who usually stuck up for anyone, just nodded, looking like he agreed.
Ruffnut sat down in the Great Hall with the other dragon trainers, unusually silent as she brooded miserably. Ruffnut knew she wasn't a obvious beauty, unlike Astrid who most people considered pretty. But still, it sucked to be compared to her all the time and always be ignored by boys. She was a girl too, despite how un-girly she often acted, and it hurt. Big time.
Ruffnut looked up to see Snoutlout and Hiccup flirt with Astrid, Hiccup subtly and awkwardly, Snoutlout vulgar and confidently, but she frowned when she saw Tuffnut and Fishlegs steal glances at Astrid too!
She stood up abruptly and stalked out the hall, before glancing back, and realising with a stab of hurt that the others hadn't even noticed she'd left.