Sasha and Ivan are two very extreme characters. Sasha, being the architypical experienced soldier, is tough, indestructible and smart one. Ivan is the younger one, lacking smarts and making up with heart. He is more reclusive and is the only friend of Dina,
Abdul's daughter, which shows that he does put himself above others. Sasha, because he was so architypically indestructible, was destined to be the one to die.