Mueller spends most of S.1202 in Liberl, acting as an attaché to the ambassador and covertly supporting Olivier while also trying, mostly unsuccessfully, to restrain his antics.
He is sent to secure the Bobcat when the Capua family and Joshua Bright attempt to recapture it. Later that year he joins the Arseille as an observer to investigate Liber Ark and joins the group that enters the Axis Pillar. When Olivier returns to Erebonia, Mueller accompanies him.
In S.1204, Mueller travels to Crossbell as Olivier's escort for the West Zemuria Trade Conference and is once again forced to restrain his companion's more extreme behavior. He fights alongside Julia Schwarz once again when the terrorist attack on the conference takes place.
Mueller is a steadfast and loyal soldier who strives to do his best for his country. As a Vander, he holds great pride in his swordsmanship and his family history.
However, his relationship with Prince Olivert Reise Arnor is a little bit complicated. While they are good friends, Mueller gets constantly irritated and exasperated by Olivert's flirtatious jokes, pranks, immature disappearing habits and having to constantly help him get him out of trouble. Despite this, he does realize that some of the stuff that Olivert does is for the good of their nation and their international relationships.
The Embassy Mission #2 - The Erebonian Embassy
After Olivier gets Estelle and co. permission to enter the embassy from the guard, they are seen entering the embassy. After the group converses for a bit, Mueller chips in with his own thoughts from his room at the embassy by saying how insulted Senator Crainagh would be to hear that. Mueller Vander then walks into the foyer and Olivier greets his bosom companion. Mueller replies that he would be better if he could cut Olivier in half and starts lecturing him on how he should let them know where he is at all times.
Olivier then jokes that its tactic in the war of love and mentions how absence makes the heart grow fonder. Major Vander then thanks Estelle and apologizes for the trouble that Olivier gives her. Estelle laughs and says that Olivier hasn't been too bad and was actually well-mannered. Mueller then asks about their business in the embassy and Estelle and co. tell him about the threatening letter.
Reminded about the letter, Vander states that he was concerned as well, but he never imagined that the Bracer Guild would be involved in the investigation too and surmises that this is a request from the army. Estelle states that it is, but they trying to investigate from a neutral standpoint. Vander commends the group for doing so and offers to show Estelle to Crainagh's office stating that it'd be better coming from him than Olivier.
The group all thank Vander while Olivier fakes being hurt again. Vander then directs them to Crainagh's office and leaves to prepare the meeting. Arriving at the door to Crainagh's office, Estelle and co. wonder if they should go in. Vander then comes out and permits them to enter. Inside the office, Crainagh welcomes the group and exchanges with Estelle and co., however, he makes an "urgh" face with Olivier and tells him not to cause so much trouble for Mueller or himself. Olivier makes a joke, but Crainagh ignores him and gets back to the subject of the letter.
He then asks the group what they want to know and Estelle asks if he has any idea on who might be behind the letter or more specifically anybody in the empire who might be against the pact. Crainagh appreciates Estelle's directness and tells her that he can think of no one who would be against it and Estelle asks if he can think of someone outside the nation who might oppose to it. Crainagh replies that he can only thinks of the opposition party in Calvard and curses the fallacies of mob rule.
Zin questions that stance and tells Crainagh that nobody would blame Rocksmith if the pact fell through and that he's certain that it has to be someone from outside Erebonia. After a brief silence, Kloe asks about Chancellor Osborne's stance on the pact. Crainagh's and Vander's interest are piqued while Oliver has to explain to a confused Estelle who Chancellor Osborne is and that he is one responsible for annexing smaller nations into the empire though less than ethical means. Hearing that, Crainagh yells at Olivier to hold his tongue and Olivier replies that he simply stated the facts and then asks that Crainagh be more cooperative since the Calvardian Embassy was helpful too.
Olivier continues to urge Crainagh and Crainagh finally responds after Mueller adds his opinion that Chancellor Osborne also approves of the pact and that he was the one who suggested that the king sign it. Estelle asks if it is because of the engine and Crainagh responds that its not and that he suggested even before the matter about the engine samples came up and that there's been no pressure to sign it. Zin then tells Estelle that it really looks like the empire isn't involved and Estelle agrees. Estelle then thanks the ambassador for his time and then asks him about Renne's parents. Crainagh replies that he hasn't heard of a visitor from Crossbell lately and Mueller replies that no one matching that description has come. Disappointed, Estelle and co. thank them and leave with Mueller showing them out.
Outside Estelle and co. exchange thanks with Mueller for his help and Mueller replies with thank yous in turn. Suddenly, Estelle notices Olivier being lost in thought and when he snaps out of it he states that its nothing. Seeing Olivier's expression, Mueller asks if Olivier is going to be staying at the embassy during his stay in Grancel and Olivier replies that he is while making an obscene joke about his and Mueller's relationship. Mueller tells Olivier to cut it out and not to give the girls the wrong impression. He then threatens to spear Olivier on the embassy's flagpole and after Olivier continues threatens to slash him in half right there.
Estelle laughs and states ".....so that's how you keep Olivier in control" and Vander expresses that them being a pair would be a terrifying thought. He then bids the group adieu and wishes them luck with the investigation. After he leaves, the group decides to head to the palace next.
The Embassy Mission #5 - Reporting the Results
Mueller is mentioned again after the investigation is over, being invited to the party that Estelle and co. were throwing at Olivier's behest. He is still mentioned being at the bar later on trying to drag Olivier back to the Embassy.
Hide and Seek - Part 2
During the 'Finding Renne' arc, Mueller is seen yet again heading off to Bose to reclaim the Capuas' airship, "The Bobcat" with Olivier seeing him off. On the airship, Mueller regrettably tells Olivier to stay out of trouble and Olivier reassures him in his own way with flirtatious jokes. Mueller gets fed up and tells him to do what he wants because he doesn't care about him and pleads with him for no international incidents. Olivier makes a suggestive joke and the airship then leaves.
Theft of the Bobcat
The scene then switches to Nebel Valley at the moment when the theft of the Bobcat happened and Mueller Vander is seen being escorted by the Guard Captain. Looking at it, Mueller notes that the ship is in perfect condition and asks if the army has been maintaining it since its capture. The Guard Captain reasons that its been used for flight practice a couple of times and he even flew it sometimes. Mueller asks how did it handle and the Guard Captain notes that it is amazing and that its speed and agility were superior to their patrol ships.
The Guard Captain then asks if it was one of the high speed model types created by the Reinford Group a couple of years ago and admits that he is surprised that the Erebonians were capable of creating such a thing since airships are normally a Liberl thing. Mueller states that he's note offended, but then notices that the armor is very thin and that it has very few weapons on it and explains to the Guard Captain that it is too expensive and non-expendable to use as a scout ship and that airships of this type have very little military value.
Seeing his point, the Guard Captain notes that it seems like a waste to just toss it and Vander continues to explain that these kinds of ships are really nothing more than toys that the nobility and newly wealthy use and that the bandits probably obtained it in a similar fashion. Hearing that the Guard Captain is reminded that the Capuas were barons and Mueller corrects him by saying "Former" barons and explains that they were stripped of their title and that the creditor who issued the original title loan on the airship wants to have it back.
Hearing that, the Guard Captain notices how messy the matter is and Mueller explains that it was their country who did Liberl a disservice and apologizes to him, but the Guard Captain replies that it is not necessary. The Guard Captain then asks when they will take it and Mueller replies in a couple days time and imagines they are busy as well. The Guard Captain laughs and admits that it is just the dregs of the old Intelligence Division and its just the thrashings of a dying beast. The Captain then boastfully claims that they'll have the Intelligence Division in lock up before the month's end.
Suddenly, a woman's voice is heard exclaiming how different the fortress was since the last time she was here and Dorothy walks up with a guard in tow. Noticing the sky pirate ship, Dorothy exclaims that its neat and tries to take a few pictures of it. The guard with her stops her, but Dorothy ditizy ways prevent him as she tries to pictures of the valley instead. The guard with her starts yelling at her and Mueller asks who she is. The Guard Captain explains that she is a reporter who forced herself in entering and writing a article on the new training ground there. He further explains that she had an appointment earlier and didn't think that she would be this late.
Dorothy then notices Mueller's uniform and asks what squad he is a member of and Mueller tries to explain, but gets interrupted by Dorothy who introduces herself. Mueller returns the greeting and Dorothy starts gushing over him and mentions that she was living in Grancel during the Hundred Days War. As they are getting to know each other, another soldier appears with a communique from headquarters warning them that there has been a change in the Intelligence Division's movements.
Later inside one of the rooms, Joshua spies on Mueller and Dorothy chatting and sharing a meal together with the soldier escorting Dorothy. They are talking about the cheap kind of military food that the Erebonian Army eats. Outside, Joshua sadly gets reminded of his friends and when Josette gets worried, Joshua insists on moving forward. Sensing a disturbance outside, Mueller goes to investigate and finds Joshua and the Capuas trying to steal the Bobcat.
Mueller declares the perfectness of this moment because it means that he can arrest the Capuas and Joshua at the same time. Josette starts panicking and Joshua explains that he briefly met Mueller some time ago. Joshua then addresses Mueller on his goals and Mueller declares that he is right, but he doesn't really care if they take the ship and fly it to the moon for all he cares. But, now that he is here now, he can't let them pass. Mueller then pulls out his sword and properly introduces himself as Major Mueller Vander of the Imperial Army's 7th Armoured Division.
Gulping, Josette pulls out her gun and Joshua warns her that it will not be a normal fight, so get ready. Mueller replies that it will be more due to him, but on your guard. The two groups then battle and Joshua and Josette barely come out the victor. Josette curses Vander while Joshua proclaims that he has figured out Olivier's identity now that Vander has revealed himself. Vander replies that his true identity was also a surprise and addresses him as "Joshua Astray.....the lost child of Hamel."
Seeing the surprise on Joshua's face, Mueller remarks that even that idiot's guesses can be right sometimes. Hearing the mention of Hamel, Joshua starts generating heavy bloodlust, freaking out Josette. Joshua asks Mueller how he knew about that and Vander notes that he does have a killer's gleam in his eyes and announces that he'll give him everything that he's got. Mueller then starts generating fighting spirit and as it looks like a battle is gonna break, the Bobcat starts up and turns around.
Popping out of the hatch, Kyle tells Josette and Joshua to hop aboard which Josette does. But, Joshua is still on the platform, finally jumping aboard with a pause as Dorothy and more soldiers run the stairs. Dorothy starts madly taking pictures, as the airship flies away with soldiers firing at it. After the Bobcat escapes, the soldiers get about cleaning up the mess and Dorothy is left wondering what is going on and decides to tell Nial what she saw. Downstairs, Mueller thinks to himself who really escaped that fight. He then thinks about Hamel and decides to help that idiot with that task.
- Mueller (nowadays written as Müller) is a German word and common last name which translates to "miller".