Meregrim is the first born of Wilmondric Shortfellow and Celsia Shortfellow (neé Brandybuck) and older brother of Merebald. 

After his mother's untimely death Meregrim's father raised him primarily in the Shortfellow smial but the family still spent a few months each year at Brandyhall, so that Meregrim would learn to know his mother’s side of the family. Being influensed by the Brandybuck's, Meregrim was more confident at the distant reaches of the Shire than the usual hobbit, this adventurous attitude would be of use to him while looking for relatives. From a young age Meregrim has shown an ambition for reuniting the family and restoring it to its golden days, this ambition caught his uncle Pello’s attention, who was head of the House at the time. And as the time came that Pello dissapeared leaving but a note telling his family he had to travell on his own for undisclosed reasons and that as he had no child of his own he wished for his nephew Meregrim to lead the family from there on. From that day Meregrim has continued Pello’s efforts of bringing the family back together.