Joan Lennon 
Leif Frond and the Viking Games [PDF ebook] 

Leif wants to be a hero, but as the youngest and smallest member of his huge Viking family, he”s never had the chance to shine. Can he finally become a champion at the Midsummer Games?
All he has to do is compete with some fully grown Viking heroes at sports including archery (no problem, with his very special bow from Queue the Artificer) and wrestling (
big problem, the other contenders are all twice his size). Oh, and keep the Widow Brownhilde away from his father before he does something stupid like marrying her. And stop his meddlesome granny from cheating. And avoid his gigantic troll-like sister and her list of chores….
Easy.