Complex sentence: His Father starts to worry that Rudolph will be made fun of because of this, his mother is more optimistic.Later they meet up with Rudolph's three uncles, Dasher, Comet and Cupid, and introduce Rudolph to them.
Split into simpler sentences: His Father starts to worry that Rudolph will be made fun of because of this, while his mother is more optimistic. Later, they meet up with Rudolph's three uncles-Dasher, Comet and Cupid-and introduce Rudolph to them.