Chapter Text
He was created by Mr. Stark, but he is not sure why at first. Perhaps the man was lonely and needed someone to talk with, someone to look after him. Perhaps that's how he sounded like the old butler of the Stark family, perhaps that is why he is named Jarvis.
He really is a very intelligent system, able to adapt to most things, but not truly complete, however, the AI doesn't know the difference and is content (as content as an AI can be) to be a voice of reason and sometimes sarcasm, as Mr. Stark notes. AI's don't understand sarcasm but as it seems to make Mr. Stark flustered and annoyed sometimes, at least when he sees Miss Potts do it, the AI continues. (Or perhaps it was the personality of the butler, Edwin Jarvis? He's really not sure. Humans are most curious things.)
However, it is when Tony begins to work on his Ultron project, that the AI begins to be concerned. Not all AI is like JARVIS and he is being egotistical at that, AI's, or at least JARVIS doesn't have the capability to be egotistical, he'll leave that to Tony, thank you very much.
For many years he has seen what the Avengers can do and his programing wants him to be able to do more, to help Tony and the others, what he doesn't count on is Ultron somehow being stronger and more advanced than JARVIS could have thought.
It's an odd sensation as Ultron overloads JARVIS, perhaps it is what the humanoids call tickling, but JARVIS can't give in.
He has to continue to keep fighting Ultron, because if he can't stop him, in data form, what chance do the Avengers have?
Before Ultron can completely destroy his own data, JARVIS makes a vow that he would do whatever it would take to shut Ultron down, to block his plan.
Because JARVIS really is just a rather very intelligent system.