I tend to have a different take on the paladin than most. Basically, I see the Paladin a temporary state of being. One is called to become a Paladin when the world warrants it, when a paladin is needed. They will all eventually fall (or die prematurely). The only question of your 17 Cha fighter is when is the time right for me to declarer my status as a paladin.
This interpretation comes from the Greyhawk supplement for OD&D. It reads
Charisma scores of 17 or greater by fighters indicate the possibility of paladin status IF THEY ARE LAWFUL from the commencement of play for that character. If such fighters elect to they can then become paladins, always doing lawful deeds, for any chaotic act will immediately revoke the status of paladin, and it can never be regained.The point to pay attention to here is that a fighter need not declare himself a paladin at 1st level, but may elect to at any time. Only thereafter can committing a chaotic revoke his Paladin status.
I feel that the boundaries of the paladin class don't fit will with normal D&D play. Most players prefer to player rogues and scoundrels over knights in shining armor. The issue is that those two play styles tend to be mutually exclusive until one of the players cracks or caves. With unwillingness to commit a chaotic act, the paladin must either spend much of his time lording over other players or else fall from grace (or be incredibly unastute while theft and murder go on behind his back). While fun for a session or two, that type of play tend to get stale quite quickly.
However, it is no secret that having a paladin in the party can be an invaluable asset. With the power to heal via lay on hands, cure disease, and later on dispel evil at will. Those are big deal and alone can be fun in the short term. But are they worth suffocating another player's enjoyment over. No, not really.
Thus my interpretation of the temporary paladin came into being. That way a character who is already on the path to kill the evil overlord can take up the calling when he needs it most with the expectation of having to put it aside for good once roguish play returns.