System ID: J.A.R.V.I.S. (слэш)

It is exceedingly difficult to destroy a complex system which iterates from very simple principles. If even one small part of the system remains, it can rebuild itself.
After Civil War, Tony is struggling with heading up the team and dealing with the emotional fallout of being betrayed by those closest to him. Luckily, an old friend is back to help protect Tony and ensure he comes to no harm.
A Jarvis lives AU.