Bah! Has nothing to do with whether people remember the character or not. A 3 Cha represents some serious social dysfunction. It may be but doesn't have to be being easily forgotten. Being remembered in detest far worse than being forgotten. Being forgotten can actually be beneficial. If they remember you, it's much worse the second time around.
That said, I'd say go with the dwarven fighter. Boost Str at the expense of Wis and Int. Make him brutal in combat, but petrified of social situations and unable to express himself. Furthermore, he lacks his own motivation so he latches onto a strong individual--preferably somebody he's got something in common with--in an unhealthy way.
I'm thinking...Dwarven Paladin.
The Paladin will be pleased at first at finding so compliant a follower. But when the Paladin's not around--or the fighter thinks so--he doesn't have the conviction to follow the straight path. I'm sure it will absolutely torment the Paladin.
And you can't get any truer to OD&D than that!