If you could choose one character from fallout 3 or fallout new vegas to return in fallout 4 who would it be and give your reasoning if you want

P.S It can't be anyone who has to dies in a main quest

Personally i hope Rose of Sharon Cassidy returns

Desmond Lockheart

This.

I think this time around he should be a potential companion who would serve as a type of mentor, insulting you whenever you set off a trap (something like "Way to go Einstein. You REALLY didn't see that mine there?"), be very strong (he would be very skilled with guns), and as a draw back he would be a dike to a lot of people. This would make quests difficult for somebody who has a low speech skill.

Caesar/Edward Swallow. Just so we can see more of the Legion, and what it's become since New Vegas.

Rose of Sharon Cassidy (Bless the character Mods ?)
[img]https://encrypted-tbn1.google.com/images?q=tbn:ANd9GcQF9a70XqbJc9ykT6PnyfXJoyA71T8oh6diIBP4KKZlVz21L-uM7w[/img]

Except he's dead.

I would love to see Charon from Fallout 3. Though he doesn't have the most in-depth background, his loyalty and the fact that he's a ghoul could add some much needed craziness and intensity. He's by far my favorite companion...

If Desmond doesn't return I will riot.

Honestly though, if Fallout 4 does take place in the Commonwealth, then a Desmond return is perfect.

Fawkes, Patches(as a question: is FO3 patches the same guy that's in Tactics?), any Great Khan.

Not in one of the endings.

If you side with him he heads north, if you side against him he and Calvert will both end up dead.

Please use http://www.gamesas.com/topic/1362764-fallout-4-speculation-suggestions-ideas-thread-58/ for FO4 suggestions.