Personality and Temperament
Relend is not inherently bad or even particularly mean-spirited, but stupid, and clumsy at social interaction. Because his friends growing up have all been boys, he doesn't know how to interact appropriately with other people his age. With Scarlet in particular, he plays pranks on her and antagonizes her, because that's how he treats his friends.
Relend was born in Sun's Beacon in N.D. 500, a few months older than Scarlet. Like her, he was a latchkey kid, with both parents working full-time throughout his childhood. He spent time first in after-school programs and later hanging out with friends. He never played any sports, but is an avid skateboarder.
Though the family lived in the inner city, they were fond of camping outdoors. Though he didn't see his parents much during the week, they would often take weekend trips into the country with their large camping trailer.
When Relend is first introduced in Heart of the Journey, he's a nuisance to Scarlet. In the second book, we find out he's recently failed the 8th grade. In N.D. 514, his family moves from Sun's Beacon to Arindell to help him start fresh and take advantage of the capitol's better school system.