Esta é a versão Westerosi da prática medieval européia de fomentar :
Later in their childhood, between the ages of 8 and 10, boys – and occasionally girls, too – of knightly and noble status would be sent away to live with another noble family for a few years in a custom called fostering. Sometimes the foster family would be related to the birth parents; William Marshal fostered with his cousin William of Tancarville. More often than not, though, foster parents were chosen for political rather than familial connections. The royal household was an especially prestigious place to foster; some royal households had upwards of 100 young men and women in their care.
Fostering helped young nobles make connections with other families while training them in the skills they would need as adult members of the aristocracy. Spending time with young people of a similar age and social class would – or so their parents hoped – strengthen the political bonds among the next generation of the nobility, and maybe even enable them to find a potential spouse.
Como Lorde do Vale, Jon Arryn foi um dos nobres mais poderosos dos Sete Reinos. Em um nível pessoal, ele era bem conhecido por sua sabedoria e senso de honra. Portanto, ele foi uma escolha lógica para promover os filhos de famílias igualmente poderosas, como os Starks e Baratheons.