Gladio lives for the sake of Lucis. After the destruction of Insomnia he leaves the party to gain the strength to protect what remains of the kingdom. He spent his entire life training to protect the royal family, to protect the subjects. He teams up with Cor, who lives by a very similar code. He promises to protect Lucis when Noctis can not.
Prompto lives for the sake of living. He had known his whole life that he wasn’t entirely human. He survives when he is separated from the party to return to them, to continue living, to prove that he is human. He teams up with Aranea, who is a mercenary that fights to live. He promises to keep living when Noctis can not.
Ignislives for the sake of Noctis. He has spent his entire life living to serve the prince and he is willing to sacrifice his life to guarantee the safety of the chosen king. He teams up with Ravus, who lives for his sister. He promises to accompany Noctis to the end.
