If one left his place while eating fruit (or other items requiring a Beracha Aharona of Boreh Nefashot), he must recite a new Beracha when he returns and wants to continue eating. In the event a person left someone else at the table, the Poskim conclude that he should not make a new Beracha. The remaining person continues his connection to the original Beracha. The Hida (Rav Haim Yosef David Azulai, 1724-1807) in Mahasik Beracha cites the Hidush of Rabbi Ya’akob Castro (1525-1610, Egypt) who rules that even if the people remaining in the original location were not eating, their continued presence alone exempts him from making a new Beracha. The Hida disagrees and brings proofs that the remaining people must also have been eating. Furthermore, the Poskim rule that if the remaining people had eaten with the person who left, but they finished eating and already recited a Beracha Aharona before he returned, he must make a new Beracha when he returns.
SUMMARY
If one left his place while eating fruit, he must recite a new Beracha when he returns, unless someone remains eating in the original place until he returns.