My friend is starting a new campaign that will be very RP heavy. I'm wanting to do a GOO Warlock and COW Bard mix to create a master of deception and mental manipulation, that is heavily based on Count of Monte Cristo. His backstory is rival family offed his family and his original Bard powers were sealed. He found a patron to Grant him new powers and to help him break the seal. So that way we can avoid having to storyline explain why after being a Lvl1 warlock he all of a sudden has Bard powers, etc. It's just his seal weakening level by level.
My question is, what advice do y'all have for order of class levels and distribution of class levels? I'm not sure how many levels we are going to wind up taking in the course of the campaign but I'm hoping to at least hit level 9 to get COW 6 shadow cloak ability and GOO pact boons. What invocations, feats, spells, level order do y'all suggest?