They shared portions of the same circulatory system and when Roberto died, Marco soon followed. Christians are to be those types of people who share. It is so easy for us to get caught up in material things and to be possessed by our possessions. But it should not be so with us. We don't live for things we live for Christ, and the things we have are only good when they are used and possessed unto the glory of God.
Sharing is more than about things however.
This passage also says that when we experience these trials we are also to keep on rejoicing. We all know something about what it means to share an inheritance at least in principal, but do you realize that if you are in Christ, you are part of this huge heavenly family that shares a common inheritance. How sad that our heavenly family, which shares this common inheritance, often looks so like earthly families that squabble with each other and fight over petty things. These are only a few of the Biblical passages that talk about the topic of sharing. Clearly, we are to share.