I'm interested to discover if there is any evidence that Justin Martyr and Marcion of Sinope had any direct or indirect contact before Marcion left the Church.
I suspect that they may have had indirect contact through writing because they were both influential and outspoken members of a relatively small educated Christian community around the same time – Marcion was 15 years older than Justin. Also, while Justin established himself in Rome, it is well known that Irenaeus of Gaul was heavily influenced by Justin's work and published his own writings only 15 years after Justin, so I suspect that Justin's work was widespread during his lifetime, perhaps early enough to be considered by Marcion.
These suspicions, however, are weakened by the fact that I do not know when Justin became widely known or when Marcion left the church. Is there any evidence that Marcion read any of Justin's works, or that the two communicated in any way, either directly or indirectly?