I couldn't find this suggested before, so I thought i'd bring it up.
In Star Wars: The Old republic, pretty early on you gain a companion that follows you through your adventures, helps you in battle, aids your personal story and provides interesting missions unique to them. Personally, I found it to be one of the most enjoyable parts of the game. There was even romance. My only gripe was their lack of customization, though it is true that you can put whatever gear you want on them.
COT is supposed to be very story driven, and I personally think it would be awesome to have a mechanic like that. Oddly, no superhero game has (that I know of) tried to apply something in this vein. DCUO offers a laughable and slightly unsettling generic child in a cape (and a shotgun..?) as a temporary pet. CO makes you buy A more useful and fleshed out sidekick, but still without the customization or story use.
What I'm hoping for is hardly something to focus on for launch, but would make a pretty cool expansion. Think of all the possibilities! Having your story introduce reoccurring characters that you grow to love, then surprising you by allowing you to take them on as full time partners! We could have classic "Save your Sidekick from 'Vengeful Madonna!'" Or even give you direct control of your sidekick in a mission to save you! (So many exclamation marks, i'm like the Shamwow guy...)
So before I vomit out anymore of my vaguely coherent ideas, are there any thoughts on this?