Work Text:
DUM-E's primary function when first created was to fetch and carry. His underlying function was to learn and adapt. This remained in place no matter what he learned or how he changed.
Over the years, he learned many things. He learned to put out fires. He learned to make smoothies (he hadn't yet learned that humans don't want motor oil in their smoothies.) He learned to be bossy towards U and to not be bossy towards JARVIS.
But no matter what else he learned or what other functions he assigned himself, sometimes, the first one was still the most important.