Thom was annoyed. Alanna had, in the past week alone, bested him in archery and slingshots, beat him in chess, stolen the book he was reading and wrestled him to the muddy ground.
Now Thom, having had his manliness brought into question, was seeking revenge on his sister. Thom put his mind to the task of coming up with a plan for retaliation and came up with a spideriffic plan.
Over the next week Thom collected spiders, lots and lots of spiders. Then when he had a whole bucket full of spiders, he snuck into Alanna's room while she was sleeping, dumped the spiders on her, and ran away.
Alanna was awakened by the spiders crawling all over her. When she saw them she leaped out of bed and ran around the castle screaming bloody murder. Then Maude caught her, brushed all the spiders off and gave her chocolate pudding to make her stop screaming.
But, alas, the pudding was too late and Alanna was so traumatized that she hated and feared spiders from that day forth.