Aloyse Von Roddenstein is a member of LOVEMUFFIN and a member of Thawne's legion of Past, Present and Future Evil and also an follower of Bill Cipher alongside Toffee, Mandarin and NOS-4A2 who he works to bring out his master
He and the others catch the heroes with intention to just kill them right then, however they are thwarted by Bruce and Selina who managed to find them and Discord manages to teleport the heroes out of the clutches. Rodney then approaches the rest of the legion and announces that Toffee is now the new ruler of the Legion after Thawne and Joker's Death
When Toffee makes his intentions to invade Mewni once again, Rodney takes front and center and leads the majority of the Cult to the castle. He also gets himself a mech of his own to command as he saw Jimmy Neutron and Lisa Loud having Mechs. With Mewni done their princess, Rodney sees a good way to curb stomp the kingdom though Bender and his friends are there and help Mewni fight back against them. Rodney's efforts manage to rather successful despite the setbacks of losing a bit of his army, Toffee however sees this as a win as the plan was achieved where he managed to destroy the High Magic Comission thus cripping the resistance. Rodney asks Toffee how he will get the spear from Bender and his friends when Bill Cipher mentions that it's not so much about him and more about someone else.
Rodney then manages to get a call to the resistance with the petirifed trophies of Dib, Bubbles, Milo, Lizbeth, Boomer, Nina, Edd, Darkwing and Starfire and tells Bender and his team to give them the spear or they will destroy them and throws the threat actually towards Lydia since she knows how to use it since Cipher knew better. In order to prove he's not bluffing he and the other members take the Starfire and fake the heroes out in killing her.
As he and the others wait, the heroes eventually arrive at their hideout, which is revealed to be at Walt Disney Land which Bill Cipher and Toffee managed to warp to their own kingdom. It becomes apparent they're not backing down so Rodney goes to kill the trophies except Alternate Doofenshimtz, Marcus and Lisa Loud all come in with their mechs to fight Rodney and the fight is a rather long one as despite them having the edge in numbers, Rodney holds off rather well and even manages to upgrade his mech in 2 other states, eventually the trio manage to find his own weak spot and bring Rodney to his knees where he pleads for mercy for his life. Marcus and Lisa both agree to give him mercy as does Alt Doof does by making him his servant when he is vaporized by an unexpected arrival from Heloise who wanted revenge for being kidnapped and forced to make a robot army for the Legion.