If the Dragonborn chooses to destroy the Dark Brotherhood, Commander Maro provides them with the pass phrase for the Falkreath Sanctuary. Alternatively, siding with the Dark Brotherhood allows the Dragonborn to assassinate Maro for an added bonus, during the assassination of the Emperor.
After the death of the Emperor's cousin, Vittoria Vici, Emperor Titus Mede II's visit to Skyrim becomes almost apparent. As the Emperor's visit approaches, he assigns his son, Gaius Maro, to verify the security of the major Holds. However, Gaius meets his demise at the hands of the Listener.
Later, Commander Maro intercepts the Listener after he or she successfully assassinates a decoy of the Emperor, after the Listener is betrayed by Astrid. Maro promised to spare Astrid and the Brotherhood if she gave up the Listener, but consumed by hatred for the Brotherhood for killing his son, Maro reneges on this deal, ordering his Penitus Oculatus agents to kill the Listener and leading the Penitus Oculatus to destroy the Falkreath Sanctuary, seeking to kill everyone in the Dark Brotherhood. The Listener escapes the wrath of Maro's agents and returns to the Sanctuary to find it in flames, kicking off the mission Death Incarnate.
The Dragonborn can choose to kill Commander Maro, although his death is optional. If the Dragonborn chooses to kill him, if he spots you when you're near him he will say, "You again!" Once on board the ship, when the Dragonborn enters the Emperor's room, Titus will state, "Well, once again I have proven Commander Maro the fool." Most likely because Maro informed the Emperor that the Dark Brotherhood was destroyed and the Emperor would have no threat on his life.
- If you choose not to kill Maro he will be at the Solitude Docks, and if you talk to him he will say "You? But you're dead! " and attack. If you retaliate, you won't get a bounty.
- After completing the quest "Destroy the Dark Brotherhood!," Maro may attend the Dragonborn's wedding. He will congratulate them on their wedding, then revert to his normal line ("I will personally inform the Emperor...").
- After you complete "Hail Sithis!" Maro may spawn in the Dragon Bridge outpost and act as if nothing has happened.
- Killing his son, Gaius, may result in getting bounty in "Commander Maro's Crime Faction". It is unknown if this is a glitch or not.