Armin

"'Oh god. Let's hope this doesn't all go horribly wrong.'"Armin is a founder from the Branch of Pictology. He appeared as an NPC in the Yummy Rleam: Part III FInale before becoming a major character at the climax and a main character in Part IV.

Yummy Rleam: Part III Finale
Armin, then known as Agent A, was an NPC on one of the new planets to appear in the finale, which was positioned between the Yummy Machine and Plantera. He wore a yellow hazmat suit that obscured most of his body. When talked to, there was a dialogue option about Jibe Turbines, to which Agent A responded something along the lines of, "I wouldn't go saying that name around here."

Right before Jibe was to finish off the remaining players at the climax, Agent A chimed in over a loudspeaker with an announcement, in response to a bright flash from the Television."'Attention, attention, all residents of Planet Yummy. I'm here to save you! On the behalf of the Branch of Pictology, this is Agent A. They call me a deus ex machin- I should probably stop rambling. Anyway, you'll now be transported to safety. Sorry I waited so long!'"Armin then teleported the players to The Oasis, leading directly into Yummy Rleam: Part IV. Armin later mentioned that it was Stallus who instructed him to wait for the last moment to intervene.

Yummy Rleam: Part IV
In the final teaser for Part IV, Armin can be heard talking to an unheard superior, probably Stallus, apparently prior to his arrival on alt-Planet Yummy. Armin says "In what world are they expected to beat Justin by themselves?" and argues that "I'm worried about them too... but bringing them here could have so many unforeseen consequeces."

Once at the Oasis, Armin gave the players a tour of the Oasis Hub and somewhat of a tutorial of quests. He briefly pulled aside Jackson and Gina to get a totally unscripted confirmation from them that they were not actually loyal to Jibe Turbines after they agreed to come to his side at the end of the Part III Finale. Following this introduction, Armin began living with the players as normal.