That seems clear enough, no? So we’re clear, I’m not interested in cases in which the character wouldn’t like the actor who portrays him; nor do I care about characters played by multiple actors in which one portrayal is so at odds with the other that it’s impossible to imagine them as friends. No, let’s stick to one actor playing multiple characters, in which the characters, if they magically met, would probably get into a fistfight seven minutes later.
I’ll begin with William Shatner. His Denny Crane might like or admire James T. Kirk, but the captain would not return the sentiment. In fact, I daresay that Kirk would think Crane was a freaking idiot, and within five minutes of the latter arriving on the Enterprise would have him confined to quarters just to keep him out of his hairpiece.
If you’re willing to admit animated cartoons, you can find examples of characters played by the same actor who can be seen actively not getting along with one another: Bugs Bunny and Yosemite Sam; Brian Griffin and Glenn Quagmire; Beavis & Butt-head and Mr. Anderson.
I really mean characters from different fictional universes; hence the remark in the OP about the characters meeting magically. Bugs & Sam strikes me as cheating, as do Brian & Quagmire. I don’t know anything about Beavis & Butthead.
I dunno. It kind of depends on where they’re meeting and which iteration of Magneto it is. Magneto is often more anti-hero than villain. If he were transported to Middle-Earth during the Ringwar, I’m fairly certain that he’d categorically despise Sauron and the Orcs. Nor I am convinced that he’d be all that tempted by the Ring, as he’d be easily capable of crushing Sauron’s armies without it. Probably before breakfast.
Then again, though, Gandalf also had enough sense to realize that the enemy of his enemy is not necessarily his friend, and that some bedfellows just aren’t worth it. I’d see Magneto in Middle Earth ending up as something a lot like Saruman.
Again, it’s going to depend on the iteration of Magneto. But it occurs to me that I myself specified that we’re talking about the movie version, so I’ll say you’re probably right and I’m probably wrong. Claremont’s Magneto would never have tried to sacrifice Rogue rather than himself as the first X-movie Mags did.
Mickey Knox and Woody Boyd probably would not be best of friends. At least not until Billy Hoyle (or Roy Munson) would come along and try to hustle them in hoops (or bowling) which would cause Mickey to kill him and Woody to help dispose of the body.
And that happy-go-lucky hippie Jesus in the movie ***Godspell ***probably wouldn’t have approved of Jennifer Garner’s deadly CIA agent dad in the TV series Alias.