My vague build started like this, with Zhentarim stuck in as well:

Level Class Base Attack Bonus Fort Save Ref Save Will Save Skills Feats Class Features
1st Fighter 1 +1 +x +x +x Intimidate 4 Feats New Class Abilities
2nd Fighter 2 +2 +x +x +x Intimidate 5 Feats New Class Abilities
3rd Fighter 3 +3 +x +x +x Intimidate 6 Scourge of the Seas [Stormwrack], Skill Focus: Intimidate Applied Force +1, Bonus Feat (Skill Focus: Intimidate)
4th Fighter 4 +4 +x +x +x Intimidate 7 Feats New Class Abilities
5th Fighter 5 +5 +x +x +x Intimidate 8, Never Outnumbered [Complete Scoundrel] Feats Applied Force +2
6th New Class Level +x +x +x +x Intimidate 9 Imperious Command [Drow of the Underdark] New Class Abilities

Planning to use Zhentarim to change the duration on Imperious Command and Scourge of the Seas was a thing, but I had real work to do and never got around to it.