Problematic player -- HELP!

[Saeviomagy]

It's been going on for quite a while. We try to reason with him to no avail. I think ONE time we got him to play some kind of mercenary for hire(neutral/neutral), and he eventually had the character suicide because he got bored of him.

Bingo. You have a winner.

Keep making him play things he's bored of and he'll leave of his own accord.

Equally effective are tactics which don't kill the character, but do change it (like helms of opposite alignment, contracting were-bear lycanthropy, being dominated and charmed, being geased etc).

MAKE him play a non-disruptive character. He'll either get the point, or he'll leave, both of which are good results.

 

[Waylander the Slayer]

Just my take...

The issue here is not your friend, but how you are handling the situation. Like others have pointed out, he is NOT a friend if he is not willing to listen to you and is being disruptive (which he is) and he absolutely has no regard or respect for you for whatever reason.

The question is WHY you consider him your friend if he has no regard or respect for you as a person and why you continue to take the abuse. Ultimately, i am sure you know the answers and the cause of all this has NOTHING to do with role playing and will never be solved with any ingame solutions.

Best o luck.