Jasper's Links
Jasper never knew that his father had another child, and, even today, he's not aware of the fact. However, one day, Jasper starts receiving letters from an anonymous person -- guarded, yet appreciative of the company, he writes back, and the two of them start a chain of letters that lead in all sorts of directions.
Marcel was relatively unaware about Jasper's existence up until he meets Tea and the gang. And even then, when he does...it's long after Jasper's been put to jail for his crimes.
After learning the truth about the father they share -- that Samuel's desire to 'fix' Marcel had only been a selfish desire to turn Marcel into a 'true' dragon -- he's anxious, but determined, to meet Jasper proper someday, and talk about their past.
Until then, while he recovers, he'll start by sending letters, unsigned.