Not sure if I'd call her incongruent or oddball from a build perspecitve, but the most complex character I played was a Glasya Tiefling. She had 5 levels of Gloom Stalker Ranger, followed by 5 levels of Divine Soul Sorcerer, then 4 Levels of Assassin Rogue, then 1 Level of Cleric of Order, then 4 levels of Battlemaster Fighter and 1 more level of rogue. She was a descendent of Asmodeus via Glasya and worshipped him as a "Necessary Evil" that deserved to be recognized for what he was - someone spending an eternity fighting a war for the benefit of all, who was due to the compensation he demanded from others for his efforts. However, she considered herself to be goodly being and spent a life of sacrifice before dying in the ultimate battle of the campaign.
She spent 20 levels trying to prove that Asmodeus should be seen not as the ultimate evil, but as someone that sacrificed for others and demanded fair compensation. This put her at odds with pretty much everyone - so in that sense she was extremely oddball. However, from a character build perspective, all the levels she took followed the concept of the character and the adventures they were undertaking.