Neoptolemus is the son of Achilles and Deidameia, a daughter of Lycomedes. His original name was Pyrrhus, but he was renamed Neoptolemus by Phoenix.
At the advice of Helenus, Odysseus and Phoenix sailed to the court of Lycomedes to retrieve Neoptolemus. The young man needed little persuasion, and was eager for the glory of war. Odysseus gave to him the armor of Achilles, which had earlier led to the death of Ajax.
Then, the three sail to Lemnos, where Philoctetes has been living for ten years, surviving only by hunting with his bow. Knowing that Philoctetes would rather kill him than leave the island, Odysseus decides to trick him. He has Neoptolemus, whom Philoctetes does not know, approach him. Neoptolemus claims that he will take Philoctetes back to Greece, and he even persuades the poor man to lend him his bow of Heracles. Philoctetes agrees.
Once on the boat, however, Neoptolemus has second thoughts about his actions. He decides to take Philoctetes back to Greece, fulfilling his earlier promise. Odysseus is upset, but the clever-talker cannot convince him otherwise. As they sail, however, Heracles, now a god, appears and commands Philoctetes to fight at Troy.
When Troy is being sacked by the Greeks, Neoptolemus kills Priam as he clings to the altar of Zeus. He apparently was not punished for this, since he was allowed to return from Troy unharmed.