Character Concept VS Min-Maxing troubles

I balance min-maxing and character concept in the opposite way of most roleplayers I suspect. First, I generate a character that makes my needs, THEN I create a concept.

I wanted a DM/Shield that dealt good single target damage in a controlled manner, but then I rationalized that he was actually Dis Pater, Roman god of the underworld, who has slowly lost godhood through lack of belief and is now using the Well to gain his powers back. When I created my TW/Elec, I just wanted a set that was survivable and good at both single target and AoE damage. That became Thundercrush, a metallic storm channeler that uses his weapon as a focus. Etc. for virtually all of my characters.