Who is Arvid from The Settlers and what is their importance?

Arvid is Robert's best friend. Over the course of the story, Robert convinces Arvid to accompany him to the gold fields of California. When their journey is delayed because of winter weather, he pleads with Robert to accompany him to Minnesota. Robert refuses this request, and they continue on their way. Arvid later dies after drinking poisonous water...... he never sees California.